Let’s Confuse Oxygen With Air Some More… What Is The Difference In Rdwc

[J Henry]

Writers and salesmen love to create confusion between air and oxygen, it so easy to play with words.

Air, oxygen and nitrogen all smell, taste and look the same so who will ever really know the difference without testing the dissolved oxygen saturation/concentration in nutrient solution – of course, no one will know the difference so let’s promote oxygen and sell some air pumps and air stones, water chillers and chemical antimicrobials. When you see the root rot you will know then you got a low oxygen problem that needs immediate attention or you can replant and start over.

Using air is always a major limiting factor of when continuous safe oxygenation is the point of the exercise. To escape the oxygen limitation in air, supplemental oxygen >20% is necessary. Supplemental oxygen comes in many cost effective forms. Beneficial microbes consume a lot of oxygen that you can first imagine to be healthy and some grower’s think healthy microbes are important for a RDWC eco system to be healthy and thrive. The more healthy microbes in your system, the greater the total oxygen demand, the more oxygen (not air) you must provide 24/7 else tour good microbes will surely get sick, they suffocate and die from lack of oxygen. That’s logical for most growers. What is not logical is the idea that air provides all the dissolved oxygen necessary to sustain 2 different eco systems in RDWC nutrient solution 24/7 form the seed germination to the harvest.

Check out this piece:

“Water temperature ranges in hydroponic systems” http://www.growersguidetocannabis.com/water-temperature-ranges-in-a-hydroponic-systems/

Why do we need to control water temperatures?

In a natural environment cannabis does not thrive submerged in water: it prefers alternate wet/dry climate (which we replicate with the wet dry cycle when growing in soil or coco-perlite) in order to drag [air] oxygen into its root system and thereby into the plant.

However when we start to adjust the natural order with an indoor grow room, and especially when using the highly artificial hydroponic method of growing cannabis, the plants’ root system needs careful manangement. If you plop a cannabis plant into a bucket of water it will die if left for a few days. This is because the root system will be unable to perform osmosis, and, deprived of oxygen [air] the plant will be unable to photosythesise and eventually it will wither and die.

(so why do cannabis growers use hydroponic systems? Quite simply because given the right conditions, hydroponics enable bigger, quicker results than any others. Hydroponic grows “mainline” the nutrients, water and [air] oxygen direct to where the plants can make use of them: the root system).

When growing with hydroponic systems there are a number of different ways to introduce [air] oxygen into the system. The main examples are:

1. DWC (Deep water culture)With DWC the [air] oxygen in the system is introduced mechanically through an air pump and air stone underneath the root system.
2. EBB & FLOW.The tray is flooded periodically, submerging pots filled with ceramic pebbles. As the water drains through, it drags all the old [air] oxygen out of the sytem and pulls in [air] oxygen rich enhanced new nutrient.
3. NFT (NUTRIENT FILM TECHNQUE)This is a system where a film of water is passed over a tray where the roots sit on a spreader mat. As the roots grow some sit submerged and others arch out of the nutrient film to reach air in a highly humid, light sealed enviroment. Some growers will also add an air stone to enhance the [air] oxygen content within the main reservoir and thereby the film of water. Dependent on the height of the trays in relation to the reservoir tank, the fall of water from the tray back to the tank can also introduce [air] oxygen. [Of course they don’t tell you that air is always 80% nitrogen and only 20% oxygen, doesn’t matter how much air you pump that all the oxygen there is in air]

So why am I talking about [air] oxygen when the subject matter is water temperature?

The temperature of water and its oxygen content are closely related, and the temperature of the solution needs to be fairly closely monitored in order to maintain dissolved oxygen levels. [most RDWC growers monitor DO by watching for root rot, a few savvy growers monitor DO with a DO Meter]

At low water temperatures, the plants go into shock, but as the temperature rises in the tank the solution loses the percentage ratio of its oxygen content. Here are some figures

tank temperature & % of oxygen in the solution (ppm) : [these ppm values are based on air exposure to the water with no concentrate in solution]

10ºc (50ºf) 13 ppm

20ºc (68ºf) 9-10 ppm

30º (86ºf) 7 ppm

As you can see the oxygen content in the resolution approximately halves for every 10ºc rise in solution temperatures. ok got that!

In easy terms, ideal temps are between 18 and 20 ºc and if your water temps are anywhere near 25 -30ºc then the oxygen levels can be as much as half of the desired levels. [these ppm values are also based on air exposure to the water with no concentrate in solution]

BUT

As a direct result of the water temperature being at higher temps the plants will need more oxygen at the roots so the problem is almost squared and there is 25-40 % less oxygen in the solution and the plants will need double the amount than normal. [these percent values are also based on air exposure to the water with no concentrate in solution]

In real terms the effect is that the oxygen level in the solution is only at 25 % of the desired levels and you can chuck as much light or feeds at them as you like but if they are only running at 25% of the required dissolved oxygen levels then this is hardly conducive to happy healthy growth is it? . [these ppm values are also based on air exposure to the water with no concentrate in solution]

Some of the results of low oxygen levels in the rez tank are: [these low oxygen problems are caused by air exposure to the water, because air simply does not contain enough oxygen to satisfy the oxygen demand]

1. roots are unable to work effectively, leading to:
2. a build up of toxins meaning that the plant will be unable to take up the water and feeds needed for healthy growth
3. The whole plant begins to deteriorate as photosynthesis and carbohydrate rates slow leading to wilting.
4. Leaf damage and root die-back. Ethylene is released and causes a toxic overdose and the roots fail.

And all of the above cause ideal conditions (especially in [low-oxygen] warm water ) for every hydroponic growers worst enemy: PYTHIUM [ROOT ROT]

[Supplemental oxygen administration is by far most direct, the quickest, easiest and very best way to completely prevent low-oxygen conditions and guarantee the highest quality oxygenation to insure plant and microbial health, if the grow needs more oxygen give the grow more oxygen; not more air, colder water or antimicrobial killer chemicals like hydrogen peroxide – supplemental oxygen administration is as simple and cost effective as safe oxygenation is ever going to get.]

J

 

[Stumpy420]

great info, will for sure up my game on watching water temperature. I'm running sugar black rose in dwc. it's the only one worth running in 1 bucket right now, out of what I currently have.

 

[PhatNuggz]

Hmmm. Air pumps, that pump air to the air stones, pull air from the ambient air in the room. If there was no oxygen in it, we would die as would our plants. Since ir pumps pump 24/7, so...

That aside, cooler water/nutrient temps hold more oxygen

 

[J Henry]

Hmmm. Air pumps, that pump air to the air stones, pull air from the ambient air in the room. If there was no oxygen in it, we would die as would our plants. Since ir pumps pump 24/7, so...

That aside, cooler water/nutrient temps hold more oxygen

 

[J Henry]

Hmmm. Air pumps, that pump air to the air stones, pull air from the ambient air in the room. If there was no oxygen in it, we would die as would our plants. Since ir pumps pump 24/7, so...

That aside, cooler water/nutrient temps hold more oxygen

Let's stop confusing aeration with oxygenation. You have missed the point of this thread so let’s try again to have a Eureka moment fellows.

If there was always plenty of oxygen in air, there would be absolutely no need for oxygen in hospitals, EMT would never carry a bottle of oxygen, they would run up to an emergency with a little battery powered electric fan and pro football players would sit in front of a big electric fan that blows lots of air instead of using and oxygen hooked to bottled oxygen. You can bet they all know the difference between air and oxygen.

Air is great fellows, but air just doesn’t have enough oxygen in it on many occasions and supplemental oxygen is really necessary to satisfy the oxygen demand.

Welders know that hooking up and air tank to a cutting torch won’t cut steel… air doesn’t have enough oxygen in it. They know air contains 20% O2, but that’s not enough O2 in many situations and air is a poor oxygenator.

 

[MGRox]

Not sure I'm totally with you here.

As you can see the oxygen content in the resolution approximately halves for every 10ºc rise in solution temperatures.

It drops by about 19-20% per 10C, it does not half. So, 11.3 ppm @ 10C // 9.2 ppm @ 20C // 7.5 ppm @ 30C.

As a direct result of the water temperature being at higher temps the plants will need more oxygen at the roots so the problem is almost squared and there is 25-40 % less oxygen in the solution and the plants will need double the amount than normal

With increasing BOD (Which we can consider roots a form of BOD too); that does not mean there is "less" oxygen. It means that oxygen is more quickly removed from said system. Thus the necessity for "replenishment" increases.
I'm not sure that you can easily state (an increase to) oxygen demand across all boards. This will be different in every situation / environment and relative to many variables.

In real terms the effect is that the oxygen level in the solution is only at 25 % of the desired levels

Again your solution is still sitting at the same saturation point. As your oxygen demand (OD) increases; you just need to replace it quicker. Until you hit a point where diffusion (with new gas) is your limiting factor.

Of course they don’t tell you that air is always 80% nitrogen and only 20% oxygen, doesn’t matter how much air you pump that all the oxygen there is in air

One of your large points, I believe, is that Air is just not sufficient to supply enough O2; correct?

Lets break this down then.
At 10C plain water can hold a max of 11.3 ppm O2. (which is to say 11.3mg of O2 per liter of water).
1 Cu. Ft of Air (plain air) contains 8.49 grams of oxygen. reference link

Just 1 cu ft of plain air contains 751 times more O2 than a liter of water can hold @ 10C; or could saturate 751 liters.
Or we could also say that per liter of water; we only need to "diffuse" 0.13% of the oxygen in air(per cu ft) to saturate.
(remember air pumps are often rated in cu.ft per minute and this is just 1 cu.ft)

The factors that are important; 1) How fast is oxygen being depleted (B.O.D., C.O.D.). 2) how quickly O2 can be replaced. With a DO and Temp reading; we could even exclude 1 and only adjust 2 if a drop in DO is noted (below saturation).

If you are concerned about replacement speed. The critical factor is diffusion of Air with water. This revolves around temp, contact time and exposed surface area (ex. bubble size). More surface area and longer contact times are your primary methods to increase diffusion to increase replacement speed.

In a 15 gallon aquarium with water pump and a single airstone; oxygen saturation levels were raised from 20% to 91% in less than 20 minutes. reference link
It would be hard for me to imagine a scenario where you would exhaust the O2 in 15 gallons of water in less than this time.

If BOD of a system were high enough to cause issues with DO levels; I would sooner fashion or buy a de-gassing column before I would go to the expense of pure O2. Extra O2 will equalize with air just as easily if a solution were above atmospheric.

 

[J Henry]

Not sure I'm totally with you here.

I appreciate your interest and your comments. Like you, I’m not totally with the author on everything he writes either.

All the points you have highlighted above as: J Henry said: originated here - “Water temperature ranges in hydroponic systems” http://www.growersguidetocannabis.com/water-temperature-ranges-in-a-hydroponic-systems/ The author and date of this publication is not identified, but I find this interesting and worthy of more discussion as fungal root rot disease is common and a problem for many gardeners. Clearly if the nutrient solution is sustained continuously at 100% DO saturation of greater, the fungal disease in inhibited and appears to be somewhat preventable in most RDWC.

But, a hobby gardener’s ability to sustain continuous DO saturation is clearly a major problem in most cases. Maybe professional growers have no fungal outbreaks and do maintain high DO continuously as they have treasure invested in this profession… or maybe pro gardeners also have root rot outbreaks too adding additional cost and personal stress.



It drops by about 19-20% per 10C, it does not half. So, 11.3 ppm @ 10C // 9.2 ppm @ 20C // 7.5 ppm @ 30C.
View attachment 581684

With increasing BOD (Which we can consider roots a form of BOD too); that does not mean there is "less" oxygen. It means that oxygen is more quickly removed from said system. Thus the necessity for "replenishment" increases.
I'm not sure that you can easily state (an increase to) oxygen demand across all boards. This will be different in every situation / environment and relative to many variables.

You did not mention the BOD of the microbial eco system that live and thrive in harmony with the hydroponic plant eco system in the nutrient solution. Additional oxygen replacement for all these little fellows is necessary too. Microbial colonies consume a considerable amount of oxygen and that BOD requires even more continuous oxygen replacement along with the roots. The collective BOD and oxygen replacement is considerable for 2 eco systems is considerable. So, all the dissolved oxygen consumed in 1 nutrient cycle must be replaced for each cycle 27/7 for months to correct the oxygen debt. Fungi are ubiquitous, they patiently wait for opportunity, any low oxygen opportunity. Pythium recognize and act on low oxygen opportunities immediately, they do not dally and thrive.

Increased nutrient temperature (environmental temperature) directly increases metabolic rates, increasing BOD and oxygen consumption proportionally for both aerobic plants and microbes. More replacement oxygen becomes necessary to sustain continuous DO Saturation and correct the oxygen debt.

Again your solution is still sitting at the same saturation point. As your oxygen demand (OD) increases; you just need to replace it quicker. Until you hit a point where diffusion (with new gas) is your limiting factor.
*** If diffusion with new gas means keep adding new air, then of course the limiting factor of oxygenation is air itself. Air contains a very low concentrations of oxygen and a high concentration of nitrogen and the barometric remains at 760 mm/hg pressure (at sea level). So if air is your limiting factor of oxygenation and this fails to reverse a low oxygen environment, it that the end of the road, are there no other options to reversing the oxygen deficit and preventing root rot? If an oxygen debt was correctable with air, there would be no need to have 100% oxygen available in hospitals. An electric fan and air conditioned room would correct any oxygen debt and provide all the oxygen a patient could ever want if that were true. I do not believe this is true or correct. Oxygen is different than air.



One of your large points, I believe, is that Air is just not sufficient to supply enough O2; correct?

What a broad brush you paint with. No that’s not my point at all so let be crystal clear regarding one of my large points leaving no room for misunderstanding. Chronic sustained hypoxia is a very serious issue for all aerobes, bar none and fungi thrive in low oxygen environments. When depending on air to insure continuous 68F nutrient DO Saturation and the BOD exceeds the oxygen demand requirements exceed the BOD for 2 synergistic eco systems in RDWC nutrient. Providing 10 times more air dissolved in the water will not reverse the oxygen deficit. The sustained O2 deficit thus insures a continuous low oxygen environment, a great opportunity for fungal opportunist.

*I believe the low oxygen environments presents ideal conditions for fungal outbreaks and other pathogens compromising health and optimal plant and microbial growth and air is often the cause of low oxygenation. RDWC gardener’s failure to sustain continuous 100% DO saturation presents great opportunity for root rot. On the other hand, low oxygenation is no problem, common, a non-issue for RDWC lettuce gardeners.

Lets break this down then.
At 10C plain water can hold a max of 11.3 ppm O2. (which is to say 11.3mg of O2 per liter of water).
1 Cu. Ft of Air (plain air) contains 8.49 grams of oxygen. reference link

Just 1 cu ft of plain air contains 751 times more O2 than a liter of water can hold @ 10C; or could saturate 751 liters.
Or we could also say that per liter of water; we only need to "diffuse" 0.13% of the oxygen in air(per cu ft) to saturate.
(remember air pumps are often rated in cu.ft per minute and this is just 1 cu.ft)
OK

The factors that are important; 1) How fast is oxygen being depleted (B.O.D., C.O.D.). 2) how quickly O2 can be replaced. With a DO and Temp reading; we could even exclude 1 and only adjust 2 if a drop in DO is noted (below saturation).

Another great point: I believe it’s important to know the BOD and C.O.D. for your garden as well as the knowing the oxygen debt for each nutrient solution cycle through a RDWC system. The savvy gardener might use a DO meter, make serial DO test and record the test results to determine if his/her DO is safe (100% DO saturation is safe, lower DO saturation is considered “low oxygen” and is considered not safe).

The hobbyist just waits and watches for symptoms of root rot and prepares for the fungal outbreak. The savvy gardener makes an initial DO saturation measurement when the solution exits the reservoir distal to the water pump (arterial/oxygenated side of the circulation system). As they said, continuous 100% DO saturation is great @ 68F water temp. Oxygen is consumed by 2 eco systems, creating a collective oxygen debt. The DO Saturation of the deoxygenated water is tested again just proximal to the water pump/reservoir (venous side of the circulation). The difference between the 2 DO Saturation test reveals the collective BOD for dual eco systems. Solvent evaporation, solute concentration, fluctuations in barometric pressure, water temp changes and other variables must be considered too when how much oxygen is required to reestablish 100% DO saturation in nutrient solution. All this is a oxygenation is generally non-issue for hobbyist gardeners.

If you are concerned about replacement speed. The critical factor is diffusion of Air with water. This revolves around temp, contact time and exposed surface area (ex. bubble size). More surface area and longer contact times are your primary methods to increase diffusion to increase replacement speed.

For clarity again: You have slipped in the word “air” when oxygen is the issue, there’s confusion again. Diffusing air and nitrogen is not the point of oxygenation, diffusing oxygen is the point and the oxygen replacement speed is vitally import to reverse the oxygen debt every nutrient cycle. The total oxygen debt clearly must be corrected and replenished every cycle to prevent a low oxygen crisis. If the oxygen deficit continue into the next circulation cycle and the next, the oxygen debt is not corrected and a sustained low oxygen environment is guaranteed… and here comes the dreaded root rot and big problems.

So if a gardener really wanted to prevent this circus of errors and disease, how would he/she prevent an oxygen debt from beginning in the first place? How would he reverse a low oxygen debt if he discovered an oxygen debt in his RDWC? The vast majority of hobbyist gardeners simply wait until the fungal symptoms of root rot present, then the realization of the outbreak is clear, the outbreak caused by low unsafe oxygenation. Without active nutrient DO testing, an outbreak is how most gardeners discover they have a low oxygen problem rotting the roots of their crop. That morning discovery always initiates “acute crisis time,” high drama and additional cost treating the disease. A real setback for the health of the crop and microbial system. I have recommendations that a popular treatment for root rot is the application of H2O2 and Clorox… kill all the beneficial microbe colonies too, kill them all with this cheap broad spectrum chemical toxin. Then spend more treasure and buy more beneficial microbes… replant the colonies and wait for another low oxygen event.

In a 15 gallon aquarium with water pump and a single airstone; oxygen saturation levels were raised from 20% to 91% in less than 20 minutes. reference link
It would be hard for me to imagine a scenario where you would exhaust the O2 in 15 gallons of water in less than this time. reference link
At best you begin with 9 points below DO saturation and that’s great for gold fish and lettuce. Again, let’s not add more confusion and refocus on the thread topic. Pivoting to salt water fish, coral reefs and oxygenation of environmental ocean water is really meaningless here. No disrespect intended, this is a common water quality pivot to aquaria fish reference. Fish need safe DO’s too.


If BOD of a system were high enough to cause issues with DO levels; I would sooner fashion or buy a de-gassing column before I would go to the expense of pure O2. Extra O2 will equalize with air just as easily if a solution were above atmospheric.

A de-gasser (no different than a spray type bait tank aerator) is certainly an option, a cheap option at that. Oxygenation using a degasser is still limited to the 20% oxygen in air and ambient oxygen tension. I fail to see how you can possibly increase the oxygen concentration in air using a degasser device, either home made or manufactured by Pentair

I really believe that grandpa Henry and his Law still controls how much oxygen will absorb in water at 1 ATM.

Pentair’s de-gasser comes with an air blower too, but the ability to oxygenated the water remains seriously limited by the low 20% O2 concentration in air even if the water is circulated through this professional manufactured degasser 100 times - 1,000 times.

If air fails to provide safe oxygenation, if more oxygen is really needed to maintain satisfy the total BOD and prevent sustained oxygen debt each nutrient cycle; if it is really necessary maintain 100% DO saturation continuously and prevent low DO insults… the simple easy way to do this is increase the FIO2, increase the oxygen tension, incorporate a simple homemade PVC packed column into the nutrient circulation systems maximize gas/nutrient interface and increase gas tension.

Now I provided you some of my thoughts and beliefs on this topic of RDWC oxygenation.

A couple question for you – your personal opinion please.

1. Do you really believe, like many others, that continuous 100% DO saturation in RDWC nutrient is vitally important to insure plant and microbial health.
   
   
2. Does low DO saturation in RDWC nutrient solution and root zones create ideal environmental opportunity for root rot outbreaks?
   
   
3. Is preventing root rot fungal disease better/cheaper than treating the rot disease post outbreak?
   

 

[MGRox]

Hard to keep up with 3 threads on this man.

A de-gasser (no different than a spray type bait tank aerator) is certainly an option,

Degassing Column. Or Packed column de-gasser. They are good at getting water to saturation DO and eliminating unwanted gasses like CO2.
Here's all you need to make one:

water remains seriously limited by the low 20% O2 concentration in air even

Again, per liter of water @10C, 1 Cu. Ft. of air at 1 atm = 751 times the amount of O2 that will fit in said water. There is gobs of extra O2 in air, relative to what water can hold.

Do you really believe, like many others, that continuous 100% DO saturation in RDWC nutrient is vitally important to insure plant and microbial health.

Plants roots like O2, so why not be at DO saturation all the time. It's very easily done with aeration.

Does low DO saturation in RDWC nutrient solution and root zones create ideal environmental opportunity for root rot outbreaks?

The ideal environment for pathogens is the same as ideal conditions for a plant. (dark, cool, moist, food, air).
Problematically low DO can inhibit or damage root growth beyond immunal response capability. The end result is an open vector (unhealthy root) for infection.
------------------------------------------------

Ok, so it's easy to get and maintain water at saturation DO. So I have to presume your meaning saturation "isn't enough".

If you are saying that you want to run "super-saturated DO" levels, then we are talking a whole other thing.
For this you need;
-An oxygen saturator (can get you to 25ml/l or so easily)
-An O2 source (tank or O2 concentrator)
Water leaving the saturator needs to NOT be agitated or disturbed as much as possible. Any exposure of the surface to air or agitation will quickly begin to drop DO.

Actually found an article on this; but relating to yield improvements rather than infection.
https://www.researchgate.net/public...rated_nutrient_solutions_on_greenhouse_tomato

Looks like they had to re-saturate every 4-5 minutes and it was difficult for them to run high levels (>30ml/l). Note even with a 30 second delivery time; the mediums residual still tested at 3-8 ml/l of O2, which was attributed to a "quick equilibrium".

 

[J Henry]

Hard to keep up with 3 threads on this man.

It may be hard for most, but you are most… you’re doing a great job keeping up.

Degassing Column. Or Packed column de-gasser. They are good at getting water to saturation DO and eliminating unwanted gasses like CO2.
Here's all you need to make one:

OK

Again, per liter of water @10C, 1 Cu. Ft. of air at 1 atm = 751 times the amount of O2 that will fit in said water. There is gobs of extra O2 in air, relative to what water can hold.

Let’s not keep omitting the importance od oxygen tension in air and apply Henry’s Law this time. At sea level oxygen tension is constant @ 159 mm/hg. Oxygen tension is a major limiting factor for dissolved oxygen saturation using even globs of air.

Plants roots like O2, so why not be at DO saturation all the time. It's very easily done with aeration.

You might want to rethink and rewrite this again. If you begin the circulation with 100% DO saturation with air (nothing to that like you say), then subtract the oxygen consumption at the terminal end of the circulation cycle (BOD of the plant eco system + the BOD of the microbial eco system = low oxygen or less below saturation.

Then you present a paradox like this, “Problematically low DO can inhibit or damage root growth beyond immunal response capability. The end result is an open vector (unhealthy root) for infection.”

The ideal environment for pathogens is the same as ideal conditions for a plant. (dark, cool, moist, food, air).
Problematically low DO can inhibit or damage root growth beyond immunal response capability. The end result is an open vector (unhealthy root) for infection.

Actually found an article on this; but relating to yield improvements rather than infection.
https://www.researchgate.net/public...rated_nutrient_solutions_on_greenhouse_tomato

This is 10 years old about tomatoes, Do you have research published in 1015-2016 regarding RDWC oxygenation Cannabis culture? Why would anyone compare tomato production to fungal prevention if RDWC cannabis gardening – preventing low oxygenation (<100% DO Saturation) in nutrient solution RDWC cannabis being the point of this matter? Thanks for the tomato article, I have not researched oxygenating tomatoes. Let's see, 75 ppm DO concentration is 75F water = 908% DO saturation and the fruit is larger. Who tomato gardeners really do this?

If you are saying that you want to run "super-saturated DO" levels, then we are talking a whole other thing.
For this you need;
-An oxygen saturator (can get you to 25ml/l or so easily)
-An O2 source (tank or O2 concentrator)
Water leaving the saturator needs to NOT be agitated or disturbed as much as possible. Any exposure of the surface to air or agitation will quickly begin to drop DO.

I agree with you on this one. The point is to insure DO Saturation continuously without low oxygen events – right? Everybody knows that chronic sustained hypoxic (low-oxygen events) are not healthy for aerobes including humans… like you said, “Problematically low DO can inhibit or damage root growth beyond immunal response capability. The end result is an open vector (unhealthy root) for infection.” When the mitochondria fail to thrive because the minimal safe concentrations of oxygen are low, that’s a real crisis.

The ideal environment for pathogens is the same as ideal conditions for a plant. (dark, cool, moist, food, air).
Problematically low DO can inhibit or damage root growth beyond immunal response capability. The end result is an open vector (unhealthy root) for infection.

***I believe you have arrived at the meat of my thread, (less than continuous 100% DO Saturation less the BOD of 2 synergistic eco systems in a RDWC cannabis garden results in low oxygen saturations < 100% DO saturation). Is root rot the infection you imply? If the infection is not fungal, what is opportunist pathogens causing this infection you speak of?

Ok, so it's easy to get and maintain water at saturation DO. So I have to presume your meaning saturation "isn't enough".

Your presumption is really very short sited and incorrect. Maintaining DO saturation seen to be the point, water chillers promote and sell a lot of product on the presumption that 100% DO sat is the ideal oxygen saturation. You are correct that DO saturation is easy with air provided there is no BOD (aerobes) consuming oxygen. It’s easy with air at any temperature. Boat salesmen promote aeration fir their boat livewells, salesmen that sell mechanical aerators in live fish bait world apply this same presumption to sell aeration, air pumps, bubble stones and water pumps the same way… and the bait dies quickly in the summer from lack of oxygen.

 

[MGRox]

It may be hard for most, but you are most… you’re doing a great job keeping up.

Was just a polite way to say that it's frowned upon to have multiple threads of the same subject and same member. No need to be disrespectful.

Let’s not keep omitting the importance od oxygen tension in air and apply Henry’s Law this time.

Henry's law is used in establishing the chart for Oxygen saturation (vs temp) that I showed previously. That chart IS accounting for the law. It is given @ 760 mm/Hg or sea level.
The only time after this that you need to re-apply the law, is when comparing the saturation levels between 2 different altitudes. Even then, a change of 2000 meters will lower the saturation from the above chart by about 20%.
Also, henry's law is for Equilibrium points. That is not inclusive of any "change over time" effects nor does it apply to any surface not exposed directly to a gas.

. If you begin the circulation with 100% DO saturation with air , then subtract the oxygen consumption at the terminal end of the circulation cycle (BOD of the plant eco system + the BOD of the microbial eco system = low oxygen or less below saturation.

Let's look at this a bit different, for 100% DO saturation maintenance:
Required Flow / Aeration = Oxygen demand of plant roots + C.O.D. + (B.O.D of medium / system - B.O.D. reduction by plant roots) **all in mg/L/hr or minute.

Then you present a paradox like this

Not a paradox when it was answering a separate question.

If the infection is not fungal, what is opportunist pathogens causing this infection you speak of?

Could also be bacterial for one.

Your presumption is really very short sited and incorrect. Maintaining DO saturation seen to be the point..........

Ok. The actual B.O.D in a RDWC is going to be pretty darn low. Your not running organics, there's not tons of biological surface area, the systems are usually cleaned somewhat often, etc. If you removed the salts from the water, the actual B.O.D. from your medium / system would be low enough to pass drinking levels anywhere. The plant roots can actually reduce B.O.D and they are used to some degree for that in wastewater.
So, primarily the oxygen demand in the system is going to be directly from the plant roots. This amount is small in comparison to closed ecosystems like fish tanks. If the actual demands were as high as your suggesting, then all land plants and aquariums would be dead from no O2.

If you are still concerned get a good quality DO meter. Test your O2 saturation level with your nutes at your altitude and temp. Use that meter to monitor O2 levels in your RDWC system. If O2 levels drop, increase exposed surface area to air (aeration, water fall, contact time, etc).

 

[J Henry]

Was just a polite way to say that it's frowned upon to have multiple threads of the same subject and same member. No need to be disrespectful.

OK. I certainly did not intend to insult you, no disrespect intended. I do enjoy our interaction. I had no idea that anyone would frown upon a forum member having multiple threads on the subject of safe oxygenation RDWC when I see how prevalent and how expensive chemicals cost to treat all these fungal outbreaks. And it’s all preventable by simply maintaining 100% DO saturation in the nutrient solution. Clearly, that is very, very difficult to do.

Let's look at this a bit different, for 100% DO saturation maintenance:
Required Flow / Aeration = Oxygen demand of plant roots + C.O.D. + (B.O.D of medium / system - B.O.D. reduction by plant roots) **all in mg/L/hr or minute.

OK, but let’s not discount the all the microbial colonies that consume oxygen. That oxygen consumption must be subtracted from saturation and replaced to correct the oxygen deficit if 100% DO saturation every circulation cycle. Depending on the size, the number and maturity of the colonies, they could easily consume more oxygen than the plants significantly increasing the total oxygen debt. Intensive recirculating aquaculture systems using a fully matured bio-filtration system, the microbes can equal or exceed the oxygen demand of the fish.

Not a paradox when it was answering a separate question.

Looked like a paradox to me.

Could also be bacterial for one.

I guess the pathogen could be anything, root rot still seems to be the most popular opportunist found in RDWC low oxygen environments.

Ok. The actual B.O.D in a RDWC is going to be pretty darn low.

Now we are coming full circle, getting to the whole point of maintaining safe oxygenation, continuous 100% DO saturation in order to prevent low oxygen insults that invite fungal outbreaks and maintaining a healthy oxygenated environment for the roots, root zoned and microbial colonies. No disrespect toward you’re opinions, but I believe you would be surprised at the BOD required by thriving matured microbial colonies. I was awed to discover how much oxygen is consumed by matured aquaculture bio-systems as well as the microbial BOD and oxygen replacement required at municipal waste water system to sustain a healthy microbes.

The plant roots can actually reduce B.O.D and they are used to some degree for that in wastewater.

If you are still concerned get a good quality DO meter. Test your O2 saturation level with your nutes at your altitude and temp. Use that meter to monitor O2 levels in your RDWC system. If O2 levels drop, increase exposed surface area to air (aeration, water fall, contact time, etc).

If you are still concerned get a good quality DO meter. Test your O2 saturation level with your nutes at your altitude and temp. Use that meter to monitor O2 levels in your RDWC system. If O2 levels drop, increase exposed surface area to air (aeration, water fall, contact time, etc).

Buying a 100% DO Meter seems logical if monitoring oxygenation is of concern. Test my nutrient DO with a DO meter.
What if my DO test reveals that my DO is low and I want to correct my low DO to a safe level, I follow your recommendation and “increase exposed surface area to air (aeration, water fall, contact time, etc).” then and retest my DO saturation and discover my oxygen saturation is still too low. What then do you recommend I do to raise the DO to saturation? Then what do your recommend I do in order to prevent the low DO problem from happening again?

I don’t think most cannabis gardeners, hobbyist or professionals, are really concerned to much about oxygenation, DO or DO meters at all. It’s clear that the average cannabis gardener would rather catch and treat their root rot outbreaks and not prevent the outbreak.

By the way, I was just wondering, do you actually know of any RDWC gardeners (hobbyist or professional growers) that have/use a DO meter? Any who have ever actually tested the DO saturation in their nutrient solution?
I know many that growers commonly deal with root rot outbreaks which they look for daily and expect outbreaks and 2 that have, use and maintain DO Saturation at 100% or greater continuously 24/7. They tell me that it is easier and cheaper to prevent root rot outbreaks than treat the disease and deal with the sick damaged plants.

The plant roots can actually reduce B.O.D and they are used to some degree for that in wastewater.

The plant roots can actually reduce B.O.D and they are used to some degree for that in wastewater.

If the actual demands were as high as your suggesting, then all land plants and aquariums would be dead from no O2.

Environmentalist are claiming that low oxygen levels are negatively affecting the Gulf of Mexico and other oceans these days. https://dl.sciencesocieties.org/publications/jeq/abstracts/30/2/320

 

[J Henry]

Fizzy farm’s oxygen pump - pumps water full of oxygen
Googling more info about safe oxygen levels and RDWC cannabis last night, I found this hydro blog

Fizzy Farms: Grow in Warmer Conditions with Ease http://www.outdoorhydro.com/blog/2013/7/18/review-fizzy-farm-dwc-grow-in-warmer-conditions-with-ease Posted on January 13, 2013 by Stewart Gregerson

Fizzy Farm’s unique technology and pump your water full of oxygen, because the reason why your plants don’t do well in really hot or really cold environments is that when the water is hot and the atoms become excited as they heat up, they retain less oxygen, meaning less of it is available to your roots. Same goes for extreme colds as well, these extremes choke out your plants and without the right amount of oxygen they don’t perform well. … rich in oxygen at 80+ or 50 and below, operate at temperatures that were previously too far off the spectrum to be tolerable.

Full of oxygen @ 80F and greater, no chillers and noisy air pumps would be unnecessary fungal outbreaks may be prevented when nutrient solution is “full of oxygen.”

What is your opinion on this oxygen technology?

 

[ken dog]

My opinion is that if you have to run your rez temperatures that high, then absolutely inject oxygen.

I do not think that oxygen is a sterilizing agent... So I don't see how it could prevent or cure anything.
On the contrary, I would think that higher rez temperatures would promote root rot growth, with or without oxygen added.

 

[MGRox]

OK, but let’s not discount the all the microbial colonies that consume oxygen. That oxygen consumption must be subtracted from saturation and replaced to correct the oxygen deficit if 100% DO saturation every circulation cycle.

Yes this was the component in that equation titled "B.O.D. medium / system"

No disrespect toward you’re opinions, but I believe you would be surprised at the BOD required by thriving matured microbial colonies.

I ran a marine reef store for several years around the turn of the century. I'm definitely familiar with this.

Test my nutrient DO with a DO meter.
What if my DO test reveals that my DO is low and I want to correct my low DO to a safe level

Yes, the point being to test your prepared solution in a separate container and aerate to saturation for your location, solution, temp etc.. This is your baseline (e.g. max saturation with no loading). If you are not happy with the level of max DO that your solution (with no load) can hold, then you must drop temp, lower EC and or use more vigorous aeration methods (degasser, or oxygen saturator).
In either case, once you establish this baseline saturation DO, then finally test your RDWC and compare how much lower your system is running than this. If you find that your (non-loaded) baseline saturation is say 9mg/l and you find the RDWC to be around 7mg/l, then Yes, increasing surface area and /or contact time can eliminate most of that 2mg/l drop.

I was just wondering, do you actually know of any RDWC gardeners (hobbyist or professional growers) that have/use a DO meter?

Guess there was one a few years ago with a meter. I know someone on here has also mentioned having tested before. Then there's a guy now setting up UC with not just a meter but a DO controller. I've not looked into the unit he's using for oxygenation, but noted being electrolytic. His thread is here:
https://www.thcfarmer.com/community...greenbeams-caught-in-the-under-current.78887/
If it was actually problematic to maintain healthy DO levels in all these hydro systems, then DO meters would be more common or required. Since it is not overly difficult, most don't ever use or need meters.

What is your opinion on this oxygen technology?

Lol he's using an aquarium pump with the "good for nothing" built in venturi haha. Naw, man that is some shady stuff there. Though, their "claims" about their pump being superior to an airstone is related to bubble size and contact time (exposed surface area relative to time), nothing more.

(in fresh type waters) Your most course bubbles are going to come from a ceramic type airstone. Then we can move to an "inline" venturi which can produce a percentage of bubbles smaller than this. Next you can go to a wood type air stone which is much finer than above. Finally you can go to a "needle wheel" type venturi pump (which works on partial cavation), this will net the finest bubbles commonly injected. Finer the bubbles, the higher its' potential efficiency to oxygenate. From an aeration perspective though, a degasser can work more efficiently than any of these above injection methods. Then finally an oxygen saturator is the highest efficiency.

Intensive recirculating aquaculture systems using a fully matured bio-filtration system, the microbes can equal or exceed the oxygen demand of the fish.

Something like this? (my old tank from around turn of the century).

80 Degree F, No chiller, No skimmer, no O2 added. 440 watts of light over 46 gallons. No DO issues.

 

[J Henry]

I've not looked into the unit he's using for oxygenation, but noted being electrolytic. His thread is here:
https://www.thcfarmer.com/community...greenbeams-caught-in-the-under-current.78887/

Thank you for suggesting this url, I’ll look into this tomorrow.

Lol he's using an aquarium pump with the "good for nothing" built in venturi haha. Naw, man that is some shady stuff there.

I’m still chuckling about this one too. My preference is a homemade packed column saturator placed in-line with the water flow. Takes 30 minutes to make it, PVC, cleaner and glue $20 and they do a great job.

Your reef looks quite impressive, no doubt your corals required meticulous care, excellent water quality and lighting. Bet you enjoyed building and managing coral eco systems like that and watching them grow. I can imagine what the reef looked like at night when the corals were in full bloom feeding. Just a few coral reef management questions please; what DO, salinity, photo-period and water temp is required to maintain a healthy reef like this?

 

[MGRox]

what DO, salinity, photo-period and water temp is required to maintain a healthy reef like this?

DO was typically in the 6.5-7.0 mg/l range on that one. Temp as stated was 80F and salinity 1.024 (s.g.). 12hr light cycle.

 

[timmur]

So I'm the guy mentioned above with a DO sensor/controller in a UC system. I wouldn't characterize maintaining DO in an RDWC as problematic necessarily, but rather as just another variable to monitor and control. Many are happy assuming that DO levels are at least to saturation, but I prefer not to leave things to chance. I'm also a guy who owns a quantum light meter and UVB light meter. Again, many are happy with round-about ways to get at light levels; I prefer to be a bit more precise.

I'm hoping to achieve at least O2 saturation during my grow and potentially even slight super saturation. O2Grow is the electrolysis device I'm going to try to control. According Dennis, the owner of the company, their system performs very well in flood and drain type systems (in terms of super saturation), but the jury is still out in RDWC systems. I will document my findings during my grow. If the O2 Grow system works well, it will be nice to get rid of the air pumps! :cool:

Ace Malawi And Cycloptics Greenbeams: Caught In The Under Current!

 

[J Henry]

So I'm the guy mentioned above with a DO sensor/controller in a UC system. I wouldn't characterize maintaining DO in an RDWC as problematic necessarily, but rather as just another variable to monitor and control. Many are happy assuming that DO levels are at least to saturation, but I prefer not to leave things to chance. I'm also a guy who owns a quantum light meter and UVB light meter. Again, many are happy with round-about ways to get at light levels; I prefer to be a bit more precise.

I'm hoping to achieve at least O2 saturation during my grow and potentially even slight super saturation. O2Grow is the electrolysis device I'm going to try to control. According Dennis, the owner of the company, their system performs very well in flood and drain type systems (in terms of super saturation), but the jury is still out in RDWC systems. I will document my findings during my grow. If the O2 Grow system works well, it will be nice to get rid of the air pumps! :cool:

Ace Malawi And Cycloptics Greenbeams: Caught In The Under Current!

Thanks for joining in timmur. There are several ways to accomplish and insure your supplemental oxygenation goals are achieved cost effectively.

https://www.thcfarmer.com/community...greenbeams-caught-in-the-under-current.78887/ and clearly you have strayed from the normal growers limitations of RDWC oxygenation. I have found little to no published research regarding intensive continuous oxygenation of RDWC cannabis/microbial colonies. There seems to be many opinions and research available regarding the negative effects of low oxygenation and sundry cures and chemicals used to treat fungal diseases. Treating the fungal outbreak is definitely far more popular than preventing the outbreak. Outbreak always result in lost time, increased expenses and significant personal stress for most hobbyist and pro growers.

There are a few of us that look beyond the limitations of the norm and imagine beyond the common limitations and we say, why not and show me… don’t just tell me. Below are points for consideration regarding this electrolysis oxygenator… the colder the water the longer the “off cycle,” the less oxygen the electrolysis device produces, the lower the DO saturation in solution. The electrolysis unit is very inexpensive and it does generate a little pure 100% oxygen and that is “the point” that justifies the advertisement.

1. Do you have a dissolved oxygen meter to test and confirm DO saturation and DO concentration in your solution? The DO meter will confirm or deny your expectations and the validity of the oxygenating product you are using-O2Grow. Compare the DO test using mechanical aeration and then retest using the electrolysis device. Test the solution at the end of the circulation cycle through the garden and see if the nutrient solution maintains DO saturation or supersaturation. The DO meter is an essential tool, anything less is simply guessing and hoping.
   
   
2. AquaInnovations Oxygenator - How Effective is It – a 3rd party scientific publication by Fishery Biologist Randy Myers Texas Parks and Wildlife Department, Inland Fisheries Division, San Antonio, TX Publication 2-14-2012 http://www.slideshare.net/raminlandfish/the-oxygenator-how-effective-is-it
   
   
3. Technical information regarding this electrolysis device used for oxygenation in another application, you will not see this tech information in infomercials, product literature or discussed by any electrolysis device salesman.
   

OXYGENATOR™ – OXYGEN GENERATOR – ELECTROLYSIS TYPE
Aqua Innovations Oxygenator™, O2 Marine Technologies, distributed by T-H Marine is an electrolysis device primarily sold and used in freshwater livewells and bait tanks. This small D/C battery operated electrical oxygen system requires (2) AA or 12 volt batteries, some units require daily maintenance after each use, new units are advertised maintenance free.

SCIENTIFIC FACTS: “The Oxygenator-How well does it work?” “How Effective is It?” Tested by Texas Parks and Wildlife Inland Fisheries Department.

TPWD, Inland Fisheries Division, San Antonio, TX Publication by Fishery Biologist Randy Myers AquaInnovations Oxygenator 2-14-2012 http://www.slideshare.net/raminlandfish/the-oxygenator-how-effective-is-it

When fish and live bait are densely crowded into livewells and bait tanks and excited during capture, handling, transport and captivity; it is absolutely is essential to provide dissolved oxygen (DO) faster than it is consumed by all the fish/bait in the livewell.

The TP&WD dissolved oxygen test were done with NO fish in the livewell water consuming oxygen [BOD – 0]. Add 1 fish and the dissolved oxygen level in the livewell water plummets drastically. Add 15-20 lbs. of fish and the oxygenator simply fails to supply a safe amount of pure oxygen to maintain minimal safe live transport DO saturation resulting in high mortality and morbidity – THE DEAD FISH PENALITY.

FACT: Although the Oxygenator does deliver 100% pure oxygen as advertised, it simply does not deliver enough pure oxygen continuously when fish are added to the livewell.

CAUTION: The gas space between a closed livewell lid and the water surface can become enriched with 3 different gases; oxygen, hydrogen, (an explosive gas like acetylene and propane) and pure 100% chlorine gas (an explosive gas) if the electrolyzed livewell water contains any salt or livewell products that contain salt. Incorporate any potential ignition source (electric wires, any live electricity) inside the livewell… EXPLOSION HAZARD / FIRE HAZARD.

Electrolysis breaks down fresh water molecules into pure hydrogen gas (H), pure oxygen gas (O2) plus deadly hydroxyl ions. If the livewell water contains any salt or livewell chemicals that contain salt, chlorine gas is always produced. Chlorine gas bubbles are visualized around the emitter as small greenish-yellow color gas bubbles (seen with back lighting). Hydrogen and oxygen bubbles are colorless.

In freshwater livewells, two thirds (2/3) of the gas bubbles produced at the emitter is pure hydrogen gas (an explosive gas) and only 1/3 of the bubbles you see are pure oxygen. Although the generator may not produce enough oxygen for all the fish or bait in the livewell, the total stocking density; it is designed, advertised and does produce [some] pure 100% oxygen by electrolysis of water. That is the sales point.

Oxygenator™ has no moving parts, makes no noise while older emitters require maintenance with special equipment after each use. Everything dies in the livewell if the oxygen live support system fails to produce or deliver enough oxygen. Summer conditions and overstocked livewells may exceed the Oxygenator™ capabilities to provide minimum safe DO saturation levels while the unit is working perfectly as advertised.

Water electrolysis produces some pure oxygen and twice as much pure hydrogen; 1:2 ratio respectively. The small volume of pure oxygen it does generate is neither regulated nor controlled by the fisherman. The small volume of oxygen generated is strictly limited, regulated and controlled by a thermometer that measures livewell water temperature.

The actual DO saturation produced with the Oxygenator™ has nothing to do with the DO saturation required to meet and sustain the minimal safe livewell oxygenation for 8-10 hours of intensive transport in overstocked summer livewell conditions.

Reduce disappointments and eliminate any unreal expectations, ask a boat dealer and Oxygenator™ salesman before the purchase – Will the Oxygenator™ provide and ensure minimal safe livewell oxygenation in the summer, keep my live bait and all my tournament fish alive all day?

Livewell oxygen systems must produce, maintain and sustain minimal continuous dissolved oxygen saturations (100% – 175% DO saturation) in a bass boat livewell, tournament weigh-in holding tank, release boat transport tanks containing a heavy limit, many limits of tournament bass (15-30 lbs fish or 400 lbs of live fish) in July/August tournaments all day long.

ELECTRICAL CURRENT may cause physiological and psychological stress impact of transporting live bait and tournament gamefish in water that’s actively being exposed to sustained low electrical current (electrolysis) in water unknown, out of sight and out of mind.

NEGATIVE AFFECTS OF ELECTROLYSIS are well know by fishermen…how electrolysis breaks down metal and electrical components on boats, motors and boat trailers. Why zinc anodes are absolutely necessary to counteract the negative effects of electrolysis.

The hallmark selling point is: “The Oxygenator ™ makes 100% pure oxygen,” Period. But, sellers will never mention if it makes enough oxygen to sustain an overcrowded livewell full of fish or live bait all day in the summer.

Technically the Oxygenator™ does qualify as a livewell oxygen system. The Oxygenator™ costs as much as a livewell water pump or small air compressor, bubble stone and air tube.

If the generator fails to produce and or sustain the minimal safe Dissolved Oxygen Saturation all day for all the catch, your gamefish and bait may die while the generator is making 100% oxygen, operating perfectly as advertised. Like when your mechanical aerator or livewell water pump is working perfectly, humming away while the tournament fish or bait are suffocating and dying as you watch in your summer livewell.

Know the facts and limitations about the Oxygenator™. Expect very limited pure oxygen production and low dissolved oxygen (DO) saturations in livewells full of gamefish and live bait every summer because the oxygen output is controlled and cycled on and off strictly by livewell water temperature. When the unit is new and functioning correctly in late fall, winter, early spring weather, the small volume of 100% oxygen may satisfy the biological oxygen demand for a small fish or a few live baits when environmental water temperature is within 40 F – 65 F.

Failure to generate enough DO is a seasonal problem like aeration, exhibited every summer when the surface water temperature reaches 75 F – 90 F. Like all mechanical aeration and water pumps, you cannot ensure minimal safe livewell DO saturation with air or the Oxygenator™ in heavily stocked livewells. Water pumps only pump water and air pumps only pump air… air and water is not oxygen regardless of how mush air and water you pump in the summer.

The water temperature sensor (the brain of the electrolyzer is a thermometer) cycles the unit on and off intermittently, the amount of oxygen that’s generated is strictly controlled by livewell water temperature not by the oxygen needs of livewells full of fish or live bait.

Add ice to cool the water and the unit cycles less generating less oxygen whether the well contains (1) three pounds of fish, (10} five pounds of fish or (15) fifteen pounds of live baitfish. Unlike standard professional fish transporters dissolved oxygen standards for transport DO protocols, livewell stocking densities are not a consideration for oxygen production and is of no concern with the Oxygenator™. That major design feature, a real plus to save electricity and battery power, can be absolutely deadly in the summer.

You can not increase the volume of 100% oxygen the unit produces and delivers which exposes an extremely limiting water quality factor like you’ve experienced with mechanical aeration: insufficient safe oxygenation.

DISSOLVED OXYGEN SATURATION RATE: Oxygenator™ literature claims to generate 80% DO saturation in 20 minutes in freshwater livewells, [no fish or bait in livewell water consuming oxygen, livewell stocking density -0-.]. This sounds great, right?

How do you think 80% DO Saturation in 20 minutes with an Oxygenator™ squares with any standard aerator or livewell water pump?

FACT: With no fish or bait in the livewell [livewell stocking density -0-.] and the standard mechanical aerators livewell pump running perfectly, 80% DO saturations or greater are easily reached within several minutes in summer livewell water. Even Mr. and Ms. Bubbles’ air pumps and bubblers can and will achieve 80% DO saturation under the same conditions in a few minutes in livewell water devoid of live bait and fish.

Oxygenator™ is popular with these freshwater boat manufacturers, OEM and by Bass Pro, Cabela’s and other major Big Box Fishing stores.

Triton Boats

Ranger Boats

G3 Boats

Nitro Boats

Champion Boats

Skeeter Boats

Tracker Boats

Stratos Boats

Bass Cat Boats

Crestliner Boats

Legend Boats

Crestliner Boats

Starcraft Marine

Procraft Boats

Weld Pro Aluminum Boats

Yar-Craft Boats

Phoenix Bass Boats

U2 LIVEWELL ADDITIVE

Oxygenator™ U2 instructions boldly state

DO NOT USE THIS DEVICE IN SALTWATER LIVEWELLS OR BAIT TANKS and DO NOT USE SALT OR ANY LIVEWELL CHEMICALS or LIVEWELL WATER CONDITIONERS THAT CONTAIN SALT.

Most livewell additives and chemicals contain salt, electrolytes that aid osmoregulation.

U2 and Salt Water U2 livewell additives are the only additives recommended for safe use with the Oxygenator™ by the manufacture. U2 literature stated the formulation contains essential electrolytes.

“Electrolyte solutions are normally formed when a physiological salt is dissolved into a solvent (water).”

What are the “essential electrolytes in livewell chemicals and formulations? Combinations of primary ions compose physiological electrolytes. Ions of Sodium (Na+), Chloride (Cl−), Potassium (K+), Calcium (Ca2+), magnesium Mg2+), Hydrogen Phosphate (HPO42−), and Hydrogen Carbonate (HCO3−). http://en.wikipedia.org/wiki/Electrolyte

Before you turn on an Oxygenator™ it is essential that you KNOW beyond any doubt whether the livewell chemical or additive you added to your livewell water contains any salt compounds.

If you are ever in doubt if any livewell additive contains salt, taste it. If you detect a salty taste, the formulation probably contains salt… Don’t turn-on your Oxygenator™.

CAUTION: Many livewell chemical manufacturers claim their fish saver livewell formulations and chemicals consist of “food grade” ingredients and may be used on food fish. Many of these products are clearly not FDA approved for use on food fish for human consumption and should never be used on tournament gamefish that are released alive after the tournament. Tournament catch and release gamefish are used for food fish for many fishermen, their wives and children.

Upon your request, any ethical livewell chemical manufacture should provide a Material Safety Data Sheet (MSDS) or complete list of formulation ingredients upon your request. All the ingredients in the MSDS should be FDA approved for use on food fish for human consumption. It’s a public healthy issue and ethical statement regarding any concern for fellow fishermen and families that may catch and eat that fish you released yesterday after the tournament – The fish that you soaked 7-8 hours in the chemical bath in your livewell.

A FISH HEALTH FACT: Hydrogen gas combines with other elements (metabolic waste) in livewell water forming noxious and very toxic hydrogen sulfide that becomes corrosive when exposed to salt, (hydrogen chloride).

 

[PhatNuggz]

I would have provided just the link, but when I entered it in the search engine weird noise started

Recirculation Basics – Part 3
By Urban Garden Magazine ⋅ April 24, 2010 ⋅ Email This Post ⋅ Print This Post ⋅ Post a comment
Filed Under air circulation, air-flow, airflow, CO2, humidity, Issue 10, Michael Christian, oxygen, temperature, ventilation
What all Hydroponic Growers Need To Know About Nutrient Recirculation

As we’ve learned in part 1 and part 2, in order to grow successfully in a hydroponic system, there are certain basics that always need to be kept in check: otherwise, plant performance inevitably suffers. After covering source water, nutrient and pH, world-renowned hydroponics expert Michael Christan breaks down the final ingredients of a healthy indoor growing environment: oxygen, light, temperature, humidity, air circulation and CO2.

Photos courtesy of AmHydro.

The 5 basics of recirculation and plant performance:

1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2

The Importance of Oxygen
It’s obvious that loose, friable soil with organic matter and thriving microbes grows plants much better than tight, clay soil devoid of organic matter. The primary missing ingredient in the latter is air (oxygen) availability.

The air we breathe is composed of gasses: 78% nitrogen (N2), 21% oxygen (02), 0.9% argon (Ar) and 0.03% carbon dioxide (CO2). The one we’re focusing on in this article is oxygen. The action of microbes on organic matter in a loose soil produces air pockets as organic matter is mineralized. These oxygen pockets are crucial to the survival and rapid colonization of healthy microbial populations. When the organic matter in the soil is fully consumed by the microbes and plants have consumed all the minerals, oxygen becomes depleted and, if more organic matter is not reapplied, plant performance slows and pathogenic (anaerobic) microbes can colonize. This condition is best avoided.

In media-based recirculating systems, the O2 is in the media: e.g. rockwool, perlite, grow rocks. Plentiful air space is available even after water is drained from the media. Roots thrive in O2-rich pockets. They are able to produce prolific root systems and plentiful root hairs to increase surface area to better absorb available ions. This is the best reason for using media with porosity. Of course, flood and drain systems suck fresh air into the media when it drains, which is why it’s such a great irrigation system.

In water-based recirculating systems, NFT, DFT and Aeroponics, O2 availability is intrinsic to the design of the system. NFT is a flat-bottomed tube with a shallow nutrient stream moving slowly, keeping root hairs moist and absorbing O2 (see “NFT Gro-Tanks,” UGM009). Aeroponics is misting droplets of water, increasing the surface area many-fold for roots to grow prolific root hairs for ion absorption. It supersaturates the solution with O2. DFT uses air pumps and water temp to keep roots bubbled with 02 and oxygen rich.

The heart of a media-based or water-based recirculating system is the nutrient reservoir. This too requires oxygenation, especially when water temperatures rise. The use of air pumps and air stones on smaller reservoirs and pump-powered eductors (venturis) on larger reservoirs make a big difference in pathogen suppression (nasty fungi and bacteria don’t like O2). This agitation drives ethylene gas from the solution and increases the longevity of the nutrient. Be sure that, if there are reservoir lids, there’s room for air exchange with ambient air in the room or greenhouse. Many commercial growers use fresh outside air in their eductors to keep the nutrient solution optimum.

Dissolved Oxygen (DO) can be measured to determine solubility of oxygen in fresh water. Fresh water at 72°F (22°C) has a DO of 8.7 ppm; at 82°F (28°C) it drops to 8.1 ppm. Salt solutions are lower. As a rule of thumb, every increase of 1ppm in DO is equivalent to an 11°F (12°C) temp drop. The cooler the temp, the higher the DO. You don’t want cold water on plant roots, though. You want 72°F (22°C) water at your roots for most plants.

When we measured DO in our greenhouse reservoirs, we found that a 74°F (23°C) nutrient tank at an EC of 2 had a DO of 6.3 ppm (low because of salts and sitting still). When we turned on an eductor (venturi), which we do in ALL reservoirs, we received a reading of 7.6 ppm. BIG difference. That’s an increase of 1.3 ppm without changing temperature.

Then we add an in-line Mazzei injector in between the tank and the feeder pipe, which raises DO to 8.3 ppm. By the time the water had run down the NFT channel and 18 plants had their way with the O2, with some off-gassing occurring, there was an 8.1 ppm DO left in the nutrient solution going back to the reservoir. That’s what we’re after! Plants thrive at those DO levels. Makes ALL the difference.

Be careful: as water temperatures of salt solutions increase, you must mitigate by adding O2 in the reservoir as well as directly on the roots. If you can’t get the DO level up by mechanical means, then you will most likely require a water chiller, which is expensive but sometimes imperative. If you cannot bring water temps down or increase DO in the nutrient solution, your next action will be disease suppression or inoculating roots with beneficials to out-compete the pathogens that thrive in high temp, low DO water. If you do get a DO meter, get a good one. We use an Extech Model 407510.

Light
Photosynthetically Active Radiation (PAR) light is a fancy term for the wavelengths plants use to vibrate chloroplasts to power the engine of photosynthesis, a vaguely understood process in my opinion. It is said that PAR light is in the 400 to 700 nanometer wavelength range. No big deal if you’re outside or in a well-lit greenhouse. But if you are growing under HID light or using it as a supplement, it certainly is.

Color temperatures of lamps are measured in degrees Kelvin from a color rendering index (CRI). The blue/white side of the spectrum has higher Kelvin temp: 6000K-8000K (MH lamps). The yellow/red side of the spectrum has lower Kelvin temperature: 3000K (HPS lamps). As a rule, the higher the Kelvin temp, the more vegetative the growth. The lower Kelvin temps are used for supplemental and/or flowering light. Different bulbs have different combinations or blends of gasses for better PAR value. Plants can be finicky and prefer one blend of light more than another. Trial and error, sometimes, is the only way to find out what your plants really like.

High Intensity Discharge (HID) lamps produce light when the gases inside the fused alumina tube are heated to the point of evaporation by high voltage electricity. This process forces the metal gasses to throw off a barrage of photons partly in the PAR range. As the bulb burns over time, the metal gasses slowly change form and degrade out of the PAR range. It is not obvious, but plant performance can suffer from lack of the PAR light when there is no shortage of photons to the naked eye. To look at light as a possible limiting factor, keep track of the hours your bulbs have been burning. If you are over the recommended burn range as stated by the manufacturer, that could be what’s compromising your system. Rule of thumb with HPS bulbs is to replace them every 12 months, and MH bulbs every 9 months, with HPS burning 12 hour days, MH burning 18 hour days.

Outside it’s obvious what limits light, like trees. But in greenhouses, if the glazing is dirty, that’s a big deal and that situation just creeps up on you. Depending on what you’re growing and what time of year it is, a dirty film can cut out as much as 30% of available light. If you are using an 85% transmission film and have 30% attributed to dirt, that’s 55%, basically shade cloth. In situations where there is too much light and plants are unable to cope with the leaf temperatures or solar radiation, a white or metallic shade cloth is preferable to black, as black can radiate heat back down on the plant canopy. A simple mistake easily avoided by many growers in double poly greenhouses is that the inflation fan is pulling inside air in between the films, thereby creating moisture that blocks light. You can tell by the droplets in between the films, or a haze. It is always recommended to use outside air for inflation. Of course, all of this is dependent on location, latitude, geography, plant in cultivation and skill/experience of the grower. We cannot cover all those variables in a brief article.

Temperature
Plant response to temperature is pretty obvious. It’s visible. Plants stop growing when root temps hit 58°F (14°C). Air temp can actually be cooler than 58°F, but when roots are cool, growth slows and stops even when air temp increases. When temps are too high, say 95°F (35°C) plus, depending on RH, air flow, light, kind, size, and age of a plant, they may stop feeding and spend their energy evaporating water from their stomata to cool down. Temperature must be managed to keep plants transpiring and active in the sweet spot.

Most temp controllers are effective, turning on fans for increased air exchanges, but when temps are too hot outside, air conditioners must be used. As a variable, though, temperature control is straightforward. It’s common knowledge that insects like very consistent temperatures and no air movement. Find which temperatures are your best high and low, and vary them morning, daytime and night. Keep an inhospitable environment for the pests without sacrificing plant performance: another dance to master.

Humidity
The two ways of explaining humidity are relative humidity (RH) and vapor pressure deficit (VPD). Most people are familiar with RH and use hygrometers so, for the purposes of this article, I will use RH.

In my experience, this is the one variable that most growers need to be more aware of. The dance between temp/humidity directly affects transpiration rates as poor transpiration opens the plant organism to disease and mineral deficiencies.

RH is the amount of water vapor present in the air expressed as a % of the amount needed for saturation at the same temperature. Here’s what that means: if the humidity is too high, e.g. 95% at 75°F, plants cannot transpire or evaporate enough water to pull minerals up the vascular system even with stomata wide open. This usually results in calcium (Ca) deficiency (remember, Ca is a non-mobile element and must be constantly supplied to growing tips) and plant stress, which increases their vulnerability to fungal intrusion.

If humidity is too low, 50% at 75°F, stomata will open in an attempt to evaporate water because of the low pressure around the leaf, but then close up to conserve cell pressure in the leaf. Plants stress as they cannot take in CO2 with closed stomata and growth stops as the plant is just trying to survive without going into wilt (i.e. loss of leaf turgidity from which it’s difficult to recover). Again the plant is vulnerable to disease and insects. These two extremes points will create a high probability of crop loss.

As a rule, at 75°F (24°C), if RH is below 60% you must add moisture to get to 75% (which is ideal), but stay below 85% to avoid stress and disease. At 85°F (29°C), if RH is below 70% you must add moisture to get to 80% (which is ideal), but stay below 90% to avoid stress and disease. As temperature rises, air holds less moisture. Steer your plants within these parameters for optimum plant performance.

When RH is too low, use a fogger or humidifier coupled with outside air exchanges. When outside air is too warm and dry, you will have to use some form of air conditioner (if that is the only way) to drop the temperature to increase the moisture-holding capacity of the air.

When RH is too high, raise temperature to reduce moisture saturation of air coupled with outside air exchanges. If outside air has too high of an RH, you will need a dehumidifier to pull water out of the air.

Transpiration is king. Monitoring transpiration rates and keeping them optimum with temp/RH manipulation is crucial. If you are outside of the temp/RH safe zones and don’t use some mechanical method of bringing them under control, you will always be fighting the results of that variable being unchecked. This is where high quality environmental controllers come in handy

You can buy the most expensive nutrients, goodies and gadgets available to grow your crop, but if your plants are unable to transpire and you don’t know that, you had best learn quickly or get a day job

Air Circulation and CO2
No matter what kind of controlled environment you’re running, greenhouse or greenroom, air circulation is another key component that is often overlooked until mildew takes out your crop or your plants starve from lack of CO2. The great outdoors takes care of all this, but inside you have to provide the controls or fall prey to what you didn’t know you didn’t know.

Rule of thumb: 60 air exchanges per hour. Not only do you need to flutter your plants with gentle breezes from an oscillating fan or horizontal air flow (HAF) fans in a greenhouse, but you must freshen the air with air exchanges from outside, taking advantage of the 385 ppm ambient CO2. The raw materials that PAR light makes into carbohydrates are CO2 and H2O. CO2 furnishes the carbon and oxygen, while water furnishes the hydrogen for the carbohydrate (CH2O).

If air exchanges are frequent, 385 ppm CO2 is plenty unless you’re looking to accelerate growth by enriching your space with higher levels to, say, 1500 ppm CO2. Even if you are adding CO2, you still must exchange air. There are numerous ways to provide CO2: chemical reactions, gas bottles, gas generators and a variety of controllers and monitors depending on the size of the operation. For the purpose of this article, you just need to know that it is a basic component of the indoor growing environment, and be mindful that it’s always available. Without CO2, plants will not grow.

One of my teachers, Grenville Stocker in NZ, took me into one of his client’s lettuce/herb greenhouses and asked me, “Would you get a chair, sit down, read a book or hang out in here all day?” Actually, it was way too moist, not enough air movement, my shirt was sticky, and it was uncomfortably warm. I said, “No way.” He remarked, “How do you think those plants feel? The same way, I reckon, except they can’t leave.” Then he showed me powdery mildew in certain areas, a thrip infestation and tip burn in some of the lettuces. The plants did not look vital, they looked stressed. I noticed the HAF fans were down, because of a blown breaker that the grower had been meaning to fix for a week. He had an RH monitor but no controller to check humidity and spill air or add heat … AND he was doing only 1 air exchange per hour because it was cold outside. He wanted to keep temps up inside without turning on the heat, which would cost him money. I looked at the RH: it was 95%. Temp was 80°F but it felt like 90°F because of the humidity. His client was too busy to pay attention or take coaching, and he wasn’t even there. Grenville always tested me; he’d say, “What’s wrong with this picture?” Then he would point out a basic that was obvious once I saw it. Most problems were easy to correct once distinguished.

I found out later the grower lost 50% of his crop and the other 50% was barely marketable. Had he kept HAF fans working, increased his air exchanges and turned up the heat to drive off the humidity with the help of a controller, he would not have had crop and financial loss. Just that one error cost him a market: he couldn’t deliver, so a competitor moved in. The point I’m making is: don’t leave your plants in an environment you can’t handle being in yourself. Use meters and controllers, but always keep them honest by paying attention to what your skin says.

All the variables of light, temperature, humidity, air circulation and CO2 must dance together in a harmony that you must monitor and control to be successful and avoid crop loss. If you cannot distinguish which variable is out, you will be guessing what the problem is and perhaps taking actions that are detrimental. Next time a problem arises (which inevitably will happen) and you’re scratching your head as to what to do, go through this list and check off each one that you KNOW is in tolerance. These 5 basics could be what you didn’t know you didn’t know. Now that you do, dissect them and become competent with each one:

The 5 basics of recirculation and plant performance:
1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2

For the content and experiences that allowed me to write these articles, I’d like to thank my teachers, Grenville Stocker (Stocker Hort), Jeff Broad (AutoGrow), Genaro Calabrese (ex partner), Grant Creevey (Accent Hydro) and all our clients and associates for sharing and being open to “figuring it out.” Controlled environment plant cultivation is infinitely beguiling; I am always learning a greater respect for being part of that process. Genaro’s motto: “Every plant, every day.”

Good luck and good growing.

Michael Christian, the president of American Hydroponics since 1984, is a hydroponic system designer and consultant to commercial growers worldwide.

 

[J Henry]

Thanks for posting this piece. American Hydroponics has great information and excellent professional consultation resources specializing in hobby and commercial hydroponic vegetable garden operations worldwide. I enjoyed spending time on their web site http://americanhydroponics.com/
No doubt that Christian and his team of experts at American Hydro are all accomplished within the hydroponic vegetable farming business specializing in lettuce, tomatoes, etc. worldwide, but I found no RDWC cannabis specialty area listed in their consultation services. Lettuce thrives in a low oxygen environment and is a popular hydroponic vegetable, easy to grow and prolific.
A bushel of high quality hydroponic lettuce or tomatoes is of course far less profitable than a bushel of high quality hydroponic medical colas.
Most RDWC cannabis amateurs and “experts” all seem to stress 100% DO saturation as ideal, the goal for oxygenation for the grow and brewing tea. These same people also talk about and write about oxygenation being less than 100% DO saturation is considered as low oxygen, not good, an open invitation inviting fungal outbreaks and other hypoxia related problems and disease.
Many say that the only way to fix a low oxygen problem is colder water and more air and the only way you find out that you have a low oxygen problem is - experience a root rot outbreak.

Have you failed to prevent the "root rot disease" in your RDWC and had to brewed up a fresh batch of tea, or used Clorox or hydrogen peroxide trying to kill it?"