yea i seen it... didnt respond cuz Charles X pretty much hit the nail on the head...

i just a little more into detail on this thread cuz it was a different topic and i was asked.

the answer to your last question in that thread may also be answered by the previous post as well :D

i dont blv it stunts them, however i would acclimate first

Loudblunts said:

LMAO authority from AN..... no seriously? thas your final answer? AN as in Advanced Nutrients?

if so..... enuff said :x

everything i posted are facts and have been around for a while...it can be googled...not to mention these are real life experiments..... The info is not tooled by some company trying to make money and hustle snake oil coughANcough

so tell me billyliar...how many Kushie Kush bottles did you buy? :)

Click to expand...

IS what my final answer?? I enquired about their nute calc, afew years back when looking into their products, and when I told them the system I was using, they (to my suprise, for the worlds most marketed company for shit products) told me to go in at 1/4 rate for bene's..
I assure you:

pythium is caused by low D.O. levels and warm reservoir

Click to expand...

this is not true.. warm water/Low DO can not form an organism.. but can help it thrive, maybe you are confusing pythium with something else??
and I personaly, aswell as other growers have used cooler res temps to slow growth in mothers.. FACT
so 19 c is a compromise for res temps...
and I dont know what kushie kush is.. if its from AN I dont and never will use them again..
peace
BL

on the contrary my friend.... if you dont think that pythium is caused by lack of DO and warm water..... i think you are the confused one my friend

let me remind you.... you are the one that thinks if you stick a UV sterilizer in your rez that it will help prevent...

keep in mind bro.... it is called ROOT rot... cant have any rot without the roots, right? therefore spraying roots with UV steriziled water would just be useless...lol

if you dont blv me, try it for yourself.... go get you some warm water and slack off on DO content levels.... then put you a UV sterilizer in the rez.... i bet more than a 100 bucks you will still get pythium

also in reference to 19C for moms....well ill give you that one, cuz im not necessarily talking about mothers nor i have extensively tested cold waters on mothers.... but then again, i dont have hydro mothers anyway... so that may be why..... but far as my aero flowering plants in 55-58F waters.... i see no stuntage in growth.... in fact quite the opposite.... bigger plants/buds

I think we have to agree to disagree here.. LOL
pythium will thrive in certain conditions, not be formed by them. you have your opinion I have mine. peace..
and I dont think that uv will help prevent any thing.. I am talking from MY EXPERIENCE, with pythium in DWC not aero.. and as mentioned earlier UV enabled me to compete a grow and not lose it.. as I have done before..
and as for trying it myself, as mentioned above I am talking from experience here..
and maybe the temps of the main of your root mass (above water) is higher than 55 f (15 c).. maybe not..
I'll leave it there..
good luck with all you do Loudblunts, you come across as a wise and interesting person. and I'm sure we'll see each other around.
Oh and I tried to post a chart on aeration efficiency but the chart was unreadable, but venturi comes up tops..
Peace and Love
Billy Liar

Billy - I will agree that if you have a bacterial, root rot, or pythium issue, UV will get you to harvest. Its a bandaid at best and is usually used when you veged without a chiller and got some rot. The thing is tho, that you still need to chill.

I have actually used UV in the past, anyone else?

billy liar said:

I think we have to agree to disagree here.. LOL
pythium will thrive in certain conditions, not be formed by them. you have your opinion I have mine. peace..
and I dont think that uv will help prevent any thing.. I am talking from MY EXPERIENCE, with pythium in DWC not aero.. and as mentioned earlier UV enabled me to compete a grow and not lose it.. as I have done before..
and as for trying it myself, as mentioned above I am talking from experience here..
and maybe the temps of the main of your root mass (above water) is higher than 55 f (15 c).. maybe not..
I'll leave it there..
good luck with all you do Loudblunts, you come across as a wise and interesting person. and I'm sure we'll see each other around.
Oh and I tried to post a chart on aeration efficiency but the chart was unreadable, but venturi comes up tops..
Peace and Love
Billy Liar

Click to expand...

o0o0o0o look at you mister class act!!! very classy! while i appreciate your compliments ill have to stay humble :D nothing special, just little ol me, LB... just like to grow my meds and help my fellow bro's and pay it forward yanno? p.s. the feeling is mutual, friend ;) :icon_spin: now enough with the mushy stuff :P :character0111:

by all means, dont let me 'joke failures' or 'strangled by internet' sarcasm get in the way. we learn from all views and out the box things.... im just confused and was asking questions.

my thing is, from what i've learned/seen/experienced pythium/rootrot comes from lack of DO and warm temperature water. Since it doesnt matter whether its hydro (dwc) or aero... its still water nonetheless right? with aero being a tad bit more picky and me not having a medium to use as a buffer..... so now that we can agree that it is water growing.... can we agree that, the nature of our growing method 'in essence' would be overwatered growing, no? This is why we use aeration and we dissolve gas into the water so we can accomplish growing in water sports, right? Whether it be by forced air injection (dwc) or aeroponics which contains dry periods for air.

So a spin off of that is.... pythium/root rot is caused by overwatering, no? If not could you explain or tell me your version of why pythium/root rot is happening?

If you agree with what said so far, than my assertion of pythium being caused by DO levels or lack thereof and warm water temperature (seeing as though DO is dependent upon water temp) would be correct, no?

again, im not saying your method of UV spraying roots wouldnt work nor am i trying to attack you friend.... i just blv we are misunderstanding each other and possibly us being 2 dogs chasing 2 completely different tails!!

this is a very good thread...lets keep it going!

Right on!

so lemme get this straight
1) pythium is virtually everywhere
2) it can survive cold temps, but wont thrive in cold temps even if given enough o2
3) warm temps and o2 will cause a bloom
4) if your plants are stressed (and likely will be if the o2 is low) then they can succomb to root rot.
5) 66F is the ideal temp to balance DO and growth rate.
6) temps as low as 55 in the res can be tolerated in AEROPONICS (this is untested in DWC and presumed to cold for DWC)
7) cold water with its associated high DO is enough to maintain a pythium free root environment in AEROPONICS, but for DWC a microbial/enzyme treatment is recommended.
8) pumps and airstones dont raise the DO in solution, this is only done with surface aggitation and cold water via Henrys Law.

Billy, i am not sure now about the criticism of ANs products. are we determining them to be inferior or something? why wont you be using their stuff anymore bro? i am considering changing to AN for my next round and following DDs nutes schedule.

1) no... MOLD/bacteria is ubiquitous, not pythium to my knowledge
2) nope.... it can survive in temps 65-67F but i do not think it can survive below those temps. DO comes into play because that is how pythium is formed.... lack of oxygen causing the plant/roots to be overwatered and/or warm water temps
3) no, warm temps and o2 cause pathogen problems, not necessarily 'bloom'. A bloom is algae and normally derived from light leaks
4) sorta.

a. if you're plants are stressed whether it be from low DO or not, they will be more susceptible to most pathogens, diseases and viruses.

b. More often than not when DO is low, plants will still be okay... just poor/slower growth.... however if DO is a problem...most likely they will not come back...once it is below the standard to sustain life.... it is most likely overwatered can or already is drowned

5) errr.... i have a problem with branding the word 'ideal' on situations like these.... however, would i grow in 66F water? nah.... have i seen slow growth rate from my 55F-58F water? nah.... im happy where im at..
6) false. water growing is water growing.... this isnt my first gro round and i've grown in many o systems and different methods including dwc. If the roots are in water, i will always keep my water cold as i feel. Medium based systems like flood and drain are less picky about root temps because the medium buffers them... and plus it isnt solid water. The only reason we are keeping/ or worrying about water being cold is because it is their medium perse. Soil and coco mediums buffer the plant and plus medium just doesnt collect pathogens as say... sitting water? or warm water?... anywho you get the idea hopefully. the only exception to this rule imo would be mediums that are used in water...which while it is a medium, it is treated differently in hydroponics/aeroponics
7)false...

a. read above response.... said it once, ill say it again....water sports are water sports.

b. enzymes arent specific to ANY one grow system.

the ONLY thing enzymes do for us is break down DEAD root material and allows that to be used. While there are other new technologies and methods that are utilizing enzymes... i.e. Bud XL which are enzymes. Used to transport/breakdown the sugars from the leafs and transfer that to the fruit/flower.... However most enzymes are root maintenance products and as i said before used to break down DEAD root matter .... products such as Canna's Cannazym, House & Garden Multizym/zen, Sensizym, Stresszyme, Hygrozyme etc etc etc....

so with all that said, DO NOT be confused about the misinformation. Enzymes are NOT a pathogen defense. They break down dead matter... dont take my word for it, do your own independent research

8) wrong. pumps and airstones DO raise D.O. in solution. the moving of the water would be surface aggitation by itself right? (however there is a limitation with this method). then air stones, if you are forcing air into a reservoir, you obviously are putting o2 in that said reservior, no? therefore, the water will dissolve the gas based on saturation which is based on your water temps.

-Cold water alone will NOT raise D.O. in any solution. Having colder water only ALLOWS/gives the ability to hold more of the gas (o2)


also, i've mentioned this once... ill say it again... it damn near impossible to get 100% maximum DO levels... because of the nature of our hobby....

we are barely going to reach 70% of our maximum.... our nutrients also work against us... the more saline the solution is, the less room for DO. This is why i suggest feeding with a low, but appropriate EC level

hope that helps

Peroxide anyone?

this is becoming laughable...
loudblunts, you seem to have a good understanding of DO..
and I agree with most of what you say on the matter, although I think it's a little irresponsible to advise these people who have invested a lot of money on these systems, to run at temps that will inhibit growth in plants.. the whole concept of recirculating hydroponics, is a design that will naturally get the nutrient solution to the point of saturation (or the equilibrium of O2 pressure in both atmosphere and water) at the temps it is running at .. taking that further to the point of super saturation has no beneficial effect on the plants, but does benefit bacteria. and a venturi is the most efficient way to get to super saturation.. more so than a 12inch waterfall effect.. or air stones...
basically the golden rule in these systems is 19c temps and high flow to keep the solution at the point of saturation..
I have been running these systems for 3 years now, for mothers and flowering plants.. and I learned from the same person that Doubled's learned from, and that person came up with the concept in the early 1990's and has been running them successfully every since.. and 19c has proven to be the optimum for this style of growing...
pythium... even dd's with his chilled res, and AC in the res room has lost plants to root rot... he posted a thread on breedbay asking for help.. it is one of the pitfalls of DWC...(ask Jalisco Kid) DD's thread at Breedbay is where he was alerted to H&G roots excell..
so my message is: people; you have a great Hydroponic design here, and is proven to work.. at the temps and flow rates that DD's uses.. So continue to follow DD's lead, and pray that Pythium does not enter your system, because it can, and giving your plant some form of protection early on is the best advice I can give... and I fully agree UV should not be used in Hydroponics unless it's to help you limp to harvest after a problem occurs..
this is my final word on the subject..
peace
BL

firstly, my humble apologies to Jack for having contributed to this [fascinating] threadjack.

primarily, i'm interested in two of the items under discussion (and to clarify, my interest is specific to dwc, and i don't care if the answers are the same or different for other methods).

1) Optimum water temperature range for growth (yield) and health, and

2) efficiency of the various methods of increasing D.O.

regarding #1, i've heard opposing opinions on optimum temperature range. i've seen great root pics and grow pics at many different temperature ranges. i have seen/heard of a lot more problems with pythium at the higher ranges. i have seen/heard of no problems with pythium at the lower ranges. this is telling me that a lower water temperature range can help me avoid bad and ugly things. i've read that around 65 degrees is the benchmark for avoiding pythium, but we know that temperatures lower than this provide higher saturation levels of D.O., so how low should we go?

some relate the experience of temps colder than 65 degrees stunting growth. some relate the opposite experience. i wonder if another factor may be at play here, such as shock. it's just recently that many growers have realized the existence of lumen shock. Imagine the scenario of a grower transferring clones from a 100 footcandle environment into a 5,000 fc environment and the plants going into shock. it might be easy for that grower to conclude that you should never put a plant into 5,000 fc. but we know that isn't the case. the truth is that plants don't like rapid changes in their environment.

i wanna see a side by side, two identical uc systems running at different water temps. and nice and easy transitions for all the ladies.

regarding #2. i've heard a lot of opinions, i wanna see some data. i just installed micro-bubble diffusor pads into my reservoir. here's a pic:



are these diffuser pads really the most energy efficient method to increase D.O.? there seem to be three methods commonly in use; waterfalls and other ways to break the surface tension (like degassing towers and different kinds of weirs), venturis, and bubblers.

i've read a number of studies regarding this issue in wastewater treatment, ponds, and fisheries. the problem is that these studies are usually at a scale very different than the scale of a dwc system. however, the most applicable information that i've found was for treating winery effluent waste. they reported the following:

Oxygen transfer rate in Different Aeration Techniques

Venturi injection - < 1 KgO2/kWhr
Surface aeration - < 1.2 – 1.8 KgO2/kWhr
Fine bubble diffused aeration - < 2.0 – 2.8 KgO2/kWhr

"Aeration systems are usually rated by the mass of oxygen transferred per kilowatt hour. The more oxygen transferred per kilowatt hour, the more energy efficient the system."

so, in this case, fine bubble diffusers are expected to be two to three times more energy efficient than venturis.

unfortunately, this doesn't completely answer my question. in my system, i already have the return to the reservoir creating a waterfall effect that doesn't cost me anything. what i don't know is if that (what i consider to be minor) surface aeration is achieving D.O. saturation and my diffused aeration is an unnecessary expense.

i would really appreciate it if someone with a D.O. meter would do an experiment which isolated this factor and gave us good data.






Papa

billy liar said:

this is becoming laughable...
loudblunts, you seem to have a good understanding of DO..
and I agree with most of what you say on the matter, although I think it's a little irresponsible to advise these people who have invested a lot of money on these systems, to run at temps that will inhibit growth in plants.. the whole concept of recirculating hydroponics, is a design that will naturally get the nutrient solution to the point of saturation (or the equilibrium of O2 pressure in both atmosphere and water) at the temps it is running at .. taking that further to the point of super saturation has no beneficial effect on the plants, but does benefit bacteria. and a venturi is the most efficient way to get to super saturation.. more so than a 12inch waterfall effect.. or air stones...
basically the golden rule in these systems is 19c temps and high flow to keep the solution at the point of saturation..
I have been running these systems for 3 years now, for mothers and flowering plants.. and I learned from the same person that Doubled's learned from, and that person came up with the concept in the early 1990's and has been running them successfully every since.. and 19c has proven to be the optimum for this style of growing...
pythium... even dd's with his chilled res, and AC in the res room has lost plants to root rot... he posted a thread on breedbay asking for help.. it is one of the pitfalls of DWC...(ask Jalisco Kid) DD's thread at Breedbay is where he was alerted to H&G roots excell..
so my message is: people; you have a great Hydroponic design here, and is proven to work.. at the temps and flow rates that DD's uses.. So continue to follow DD's lead, and pray that Pythium does not enter your system, because it can, and giving your plant some form of protection early on is the best advice I can give... and I fully agree UV should not be used in Hydroponics unless it's to help you limp to harvest after a problem occurs..
this is my final word on the subject..
peace
BL

Click to expand...

lmao.... so when somebody ELSE ask for my opinion.... you happen to get a stick up your ass because YOU dont blv it... or because im not DD, yet i bet 2 grand that if DD had said it, you'd be on his peter faster than the speed of light itself.

i find it hella funny, not to mention, HIGHLY condenscending for you to say that you agree with most of everything i just said... then for you to turn around and say ' oh no, just follow DD's lead '..... you say that like this is a cult or something and one must follow a cult leader. While DD is a great grower and puts out outstanding results.... to imply or bluntly state to only 'follow' DD results is, well, like you put it, 'laughable'. DD nor the 'person' who showed you and him are not the inventors of some new technology. If this is the case... then im sure its no better than Stinkbud and his little cult affiliation with folks thinking he invented aero/nft hybrids.

I've done tons of study and real life test on D.O. levels...not to mention me having a person in my corner who is a botanist AND works with water and water treatments....so i tend to take my experiences not so lightly

Now i have no problem if you disagree with me.... but do that and present your case with facts and your findings/experience, no? That would seem like the debate winner instead of saying some shit like "just follow DD's lead".... for 1) who does that help? just follow somebody else lead? what about the ones who dont just wanna follow somebody else lead and want to know the answer for themselves? 3) dont you think we all could learn from this, including me? i mean if you think im wrong just state your case instead of doing what was previously stated

Like i said before DD has some nice stuff and puts out some amazing product..... but again, who died and made DD the hydro king? or even Jalisco Kid for that matter. I dont think DD is that cocky and he is humble enough not to accept or even WANT that title.

last but not least... you bring up irresponsible.... thas kinda odd, dontcha think? only thing irresponsible i see is someone else telling another person in a totally different setting/environment to "follow DD's lead" when you and I both know no two OP will be the same, even with the same equipment.

;) anywho, have a great day, 'friend' :)

Papa said:

firstly, my humble apologies to Jack for having contributed to this [fascinating] threadjack.

primarily, i'm interested in two of the items under discussion (and to clarify, my interest is specific to dwc, and i don't care if the answers are the same or different for other methods).

1) Optimum water temperature range for growth (yield) and health, and

2) efficiency of the various methods of increasing D.O.

regarding #1, i've heard opposing opinions on optimum temperature range. i've seen great root pics and grow pics at many different temperature ranges. i have seen/heard of a lot more problems with pythium at the higher ranges. i have seen/heard of no problems with pythium at the lower ranges. this is telling me that a lower water temperature range can help me avoid bad and ugly things. i've read that around 65 degrees is the benchmark for avoiding pythium, but we know that temperatures lower than this provide higher saturation levels of D.O., so how low should we go?

some relate the experience of temps colder than 65 degrees stunting growth. some relate the opposite experience. i wonder if another factor may be at play here, such as shock. it's just recently that many growers have realized the existence of lumen shock. Imagine the scenario of a grower transferring clones from a 100 footcandle environment into a 5,000 fc environment and the plants going into shock. it might be easy for that grower to conclude that you should never put a plant into 5,000 fc. but we know that isn't the case. the truth is that plants don't like rapid changes in their environment.

i wanna see a side by side, two identical uc systems running at different water temps. and nice and easy transitions for all the ladies.

regarding #2. i've heard a lot of opinions, i wanna see some data. i just installed micro-bubble diffusor pads into my reservoir. here's a pic:

are these diffuser pads really the most energy efficient method to increase D.O.? there seem to be three methods commonly in use; waterfalls and other ways to break the surface tension (like degassing towers and different kinds of weirs), venturis, and bubblers.

i've read a number of studies regarding this issue in wastewater treatment, ponds, and fisheries. the problem is that these studies are usually at a scale very different than the scale of a dwc system. however, the most applicable information that i've found was for treating winery effluent waste. they reported the following:

Oxygen transfer rate in Different Aeration Techniques

Venturi injection - < 1 KgO2/kWhr
Surface aeration - < 1.2 – 1.8 KgO2/kWhr
Fine bubble diffused aeration - < 2.0 – 2.8 KgO2/kWhr

"Aeration systems are usually rated by the mass of oxygen transferred per kilowatt hour. The more oxygen transferred per kilowatt hour, the more energy efficient the system."

so, in this case, fine bubble diffusers are expected to be two to three times more energy efficient than venturis.

unfortunately, this doesn't completely answer my question. in my system, i already have the return to the reservoir creating a waterfall effect that doesn't cost me anything. what i don't know is if that (what i consider to be minor) surface aeration is achieving D.O. saturation and my diffused aeration is an unnecessary expense.

i would really appreciate it if someone with a D.O. meter would do an experiment which isolated this factor and gave us good data.






Papa

Click to expand...

dont know if you want my input but im about to get some uc 8 and start testing that myself... i wanted to see if i could reach higher with them

ill PM you the answers to your questions if you like....just let me know if you want my input......
dont want to be 'insulting' anybody or being 'irresponsible' LMAO

Loudblunts.

yes, please.











Papa

Papa,
what the...
i cant tell, but it looks like a dude is INSIDE your reservoir, whats going on here?

Loudblunts- please stay with us, I am interested in what you have to say, and I am also interested in hearing conflicting opinions and appreciate a forum where people can feel free to speak freely without fear of ridicule or abusive responses. i would hate to make ANYONE feel that their opinion is not valid, or that they arent intelligent.

Ok I have sent a pm to loudblunts, apologising for the cut downs.. but I still stand by most of what I have said. The main thing I will take back is the fact that Pythium thrives in DO rich water.. this does seem to be Not true..
But I will reiterate that Pythium is every where.. and is probably in your system already. Also 19c is as good as you can get as a compromise for root efficiency and DO content..
I have copied and pasted a document I read whilst I was struggling with a pythium infection a few years ago. I regret that my memory has let me down a little over the last few years.. Cant imagine why..:afroweed:
one thing I was thinking at the start of this debate, is that running aero, means dry periods, meaning, extremely high oxygenation to roots.. thus reducing the chance of damage caused by periods of oxygen starvation.. Like we are susceptible to in recirculating DWC.. My problem was caused by very warm nute temps. therefore very low oxygen content, even with pumps running, and what would of otherwise been a very healthy system.. (make sure your chiller does not fail)
My main reason for stepping into this thread is that people running this type of system need to have a good understanding of what is happening in the system.. And why its happening.. and the main difference between loudblunts and myself, is the wording of what we are trying to say.. rather than pythium being caused by low DO and high temps, these are the conditions that allow Pythium to take hold of root systems..
please have a read of this article, its very informative.


Nutrient Temperature, Oxygen and Pythium in Hydroponics

by Dr Lynette Morgan

The hydroponic nutrient solution is not just a mix of fertiliser salts and water, there are a number of organisms and compounds commonly found in our hydroponic systems that we need to be aware of. One of the most important of these is dissolved oxygen which is vital for the health and strength of the root system as well as being necessary for nutrient uptake.

Most growers are familiar with the need to have some form of aeration in their nutrient solution - whether they be in a recirculating or a media based system. In NFT systems, this is often accomplished with the use of an air pump or by allowing the nutrient to fall back into the reservoir thus introducing oxygen. However, the effect of temperature of the solution on the dissolved oxygen levels and on root respiration rates also needs to be taken into account. As the temperature of your nutrient solution increases, the ability of that solution to `hold' dissolved oxygen decreases. For example, the oxygen content of a fully aerated solution at 10C (50 F) is about 13ppm, but as the solution warms up to 20 C (68 F) the ability of the liquid to `hold' oxygen drops to 9 - 10ppm, by the time the solution has reached 30 C (86 F), then it's only 7ppm.

While this may not seem like a huge drop in the amount of dissolved oxygen, we have to remember that as the temperature of the root system warms, the rate of respiration of the root tissue also increases and more oxygen is required by the plant. For example, the respiration rate of the roots will double for each 10C rise in temperature up to 30C (86 F). So the situation can develop where the solution temperature increases from 20 - 30C (68 - 86 F) during the day, with a mature crop and a large root system, then the requirement for oxygen will double while the oxygen carrying capacity of the solution will drop by over 25%. This means that the dissolved oxygen in solution will be much more rapidly depleted and the plants can suffer from oxygen starvation for a period of time.

The symptoms of oxygen starvation which can occur in both NFT and media based systems can be difficult to pick up as they are very general signs. Media based plants are just as prone to oxygen starvation in hydroponic systems as those grown in solution culture, but here we must also take into account the `air filled porosity' of the media used. This is simply how much air can permeate between the particles in the substrate and selection of a free draining media which won't break down will ensure that maximum aeration is going to reach the root zone. Injury from low (or no) oxygen in the root zone can take several forms and these will differ in severity between species. Often the first sign of inadequate oxygen supply to the roots is wilting of the plant during the warmest part of the day when temperature and light levels are highest. Insufficient oxygen reduces the permeability of roots to water and there will be the accumulation of toxins, thus both water and minerals cannot be absorbed in sufficient quantities to support plant growth particularly under stress conditions. This wilting is accompanied by slower rates of photosynthesis and carbohydrate transfer, so that over time, plant growth is reduced and yields will be affected. If oxygen starvation continues, mineral deficiencies will begin to show, roots will die back and plants will become stunted. Under continuing anaerobic conditions, plants produce a stress hormone - ethylene which accumulates in the roots and causes collapse of the root cells. Once root deterioratation caused by anaerobic conditions has begun, opportunist pathogens such as Pythium can easily take hold and rapidly destroy the plant.

Another more visible and longer term effect of oxygen starvation which also occurs in waterlogged crops is leaf `epinasty'. Epinasty is a downward curvature of the plant leaves, resulting in plants which look wilted. If the oxygen starvation continues and is severe, then eventually leaf chlorosis yellowing, premature leaf and flower abscission will occur.

There are a number of things we can do to make sure our nutrient solution is carrying sufficient dissolved oxygen, and this is important when we consider that many of the root diseases encountered in hydroponics have occurred because the root system was damaged in some way, with anaerobic conditions being a major factor in many situations. The first most important factor to remember with oxygen is that the best way to introduce this gas into the nutrient is to have the solution fall back into the reservoir, and the greater the drop height, the better the aeration effect. Breaking the flow up into a fine shower also assists by introducing more air bubbles into the tank. Secondly, while nutrient EC does reduce the oxygen carrying capacity of the solution, the effect is very small and temperature has a much greater influence on oxygenation. Reducing excessive solution temperatures will ensure more oxygen can be held by the solution and the rate of respiration by the roots will be kept down to optimal levels. Thirdly factors such as nutrient flow rate, channel width, length and slope have a large effect on oxygen levels- faster flow rates, greater slopes and shorter channel lengths all assist with prevention of oxygen starvation.

Perhaps one of the commonest problems in hydroponic systems is the Pythium pathogen and what many growers don't realise is that Pythium being an `opportunist' fungi, often takes advantage of plants which have been stressed by a combination of high temperatures and oxygen starvation in the root zone. Pythium is usually described as a `secondary infection' meaning that the Pythium spores which are actually common in just about all hydroponic systems, don't actually attack the plant until it has been damaged in some way. Even very clean hydroponic systems and grow rooms which are isolated from the outdoor environment will have some Pythium present as these fungal spores are naturally present everywhere on a world wide scale - in the water, soil, vegetation, carried in the air and in dust, so its difficult to eliminate the source of this disease. However, one way we can reduce the `spore load' is to sterilise any water supply which may be contaminated with high levels of pythium - water from dams, and streams should always be sterilised before use for this reason if Pythium is a problem.

Under the right environmental conditions, virtually every plant species is vulnerable to Pythium, which not only causes `damping off' of seedlings but causes root and stem rot of older plants. Symptoms of Pythium on older plants are a wet rot, root systems will be browned, roots hollow and collapsed. Plants may appear to grow poorly, and wilt for no apparent reason - indicating that an examination of the root system is called for. Pythium has an optimum temperature range for infection of plants, this is generally between 20 - 30C (68 - 86 F), although infection can occur outside this range when damaged plant tissue is available for rapid colonisation by the pathogen. Low concentrations of Pythium that may not cause problems at lower temperatures will be disastrous at higher temperatures, particularly where the warmer conditions are associated with a lack of oxygen in the root zone and plant stress.

The best preventative measure against Pythium attack is a healthy, rapidly growing plant as this is an opportunist pathogen and will enter at the site of tissue injury or if the plants are overly succulent, weakened or stressed for some reason. Often root damage during the seedling stage as plants are introduced to the hydroponic system is a danger time for Pythium infection. Pythium is of greatest threat during the seed germination and seedling development stage when plants are most vulnerable to attack, and adequate control and elimination of the pathogen during this stage is the best preventative measure of Pythium control in hydroponic systems. Strong healthy plants will develop resistance to Pythium attack during the seedling stage and this will prevent problems at a later stage of growth.

Other preventative measures include the use of a well drained media, thorough disinfection of all equipment between crops (a strong hypochlorite solution - bleach is the most effective), and control of pathogens during the seedling stages with a suitable fungicide, long before they are introducing into your hydroponic system. Occasionally a very high spore load, combined with excessive temperature will result in Pythium attacking even healthy plants, if this is the case, it is likely that there is an active source of spore production present, and the system must be shut down and disinfected. Some growers have found the use of wetting agents and chlorination of the nutrient solution beneficial in limiting the damage caused by Pythium, however extreme care needs to be taken when using products such as calcium hypochlorite as to much active chlorine will kill sensitive plants. UV light, hydrogen peroxide and ozone have also been used to kill Pythium spores in the solution, however these can have major effects on some of the nutrient elements in solution and careful consideration should be given before using these methods. Sterilisation of the water supply with these methods, before nutrient are added however, is effective at reducing or eliminating Pythium from the original water supply.

Therefore by ensuring your plants are healthy and stress free, you will not only get the highest growth rates possible, but also prevent problems such as Pythium infection occurring. The variables to remember with regard to the nutrient solution is that aeration is vital to maintain the dissolved oxygen levels, temperatures should be keep within an optimum range, and Pythium is always present, but a healthy plant is the best measure of protection against a disease outbreak. About the oxygen requirement of plants when in flower...its not always the case that plants require more oxygen because they are in flower, a plants oxygen requirement is linked to the size of the root system, temperature and nutrient uptake rates, rather than the presence of flowering. So since plants such as tomatoes tend to have a rapidly developing root system at the time of flowering, its important to maintain adequate oxygen levels. With tomatoes the requirement of oxygen in the root zone increases gradually up until the time of maximum fruit load and rapid fruit expansion, where the high rates of nutrient uptake increase the oxygen requirement quite dramatically. On the other hand, if oxygen is deficient during flowering, then the flowers and subsequent fruit may drop off as a result, or they may be undersized and may fail to pollinate.


So thats mainly what my understanding is based upon..
on the efficiency of aeration techniques, my beliefs are based upon tests done in small garden ponds of similar volumes to the systems we run here.. heres a linkhttp://web.archive.org/web/20050828062718/http://home.att.net/~oxymax/aerate.htm
I am not a Doubled's groupie as some here admittedly are. I was actually quite surprised when I saw DD's system a year or so ago, and noticed how very similar it is to the system I use..
Once again I sincerely apologise if I offended anyone here.. And although loudblunts and I are singing from the same hymn sheet, we have used differing terminology to get our message across..
peace and trees
Billy Liar

jack the reaper said:

Papa,
what the...
i cant tell, but it looks like a dude is INSIDE your reservoir, whats going on here?

Click to expand...

[grin] . . . just dreaming.




that's a reservoir for treating waste, about 30,000 gallons, with a couple of hundred diffusers. can you imagine the dwc system you'd be running with a reservoir this scale?








Papa

thanks for the post Billy, i want to read it all over dinner.

papa, i thought that might have been waste treatment, i also imagined you wearing hip waders in there with a bunch of floating pots! that would be crazy!!:banana1sv6:

Thanks for the info billy....Great article...

Loudblunts- You are in dd mpb forum so who cares if we follow his lead or not...With the amount of $ being invested in these systems you better believe I am going to follow his blueprint with almost no deviations..

mc




mc