PH A Basic explanation

[Aqua Man]

It's nice finding people who like talking about science. I majored in Molecular Bio in college and didn't end up working in that field so I miss it sometimes. I have very little practical knowledge of ph regarding growing, I only ever tried growing with synthetics once and lets just say its not for me. And I don't really whip about the ph meter for organics.

You find plenty of ppl on here with great discussions on all sorts of things. Collectively we have one hellova knowledge base. And likewise it's always nice to discuss and learn.

 

[Frankster]

One thing to note is that microbes do not just moderate the ph of your soil, but catalyze reactions on both sides of the ph scale by producing enzymes with active sites that work by simulating the ideal ph for a specific reaction. So a healthy soil would still test at a certain ph but it effectively operates on a wider ph range than a lifeless soil.

Yes, exactly, because the pH range is going to effectively be different rates at different sites within the soil itself. The top layer pH can have little to do with what's actually happening down around root level, especially if additives have been introduced, but also altered by the accumulation of inorganic salts, buildups and or waste products left behind from enzyme catalyzed reactions during the lifecycle of the plant. So, I think a living soil approach has it's big advantages in it's ability to "self regulate" the pH to some degree, and allows for a more natural (constellation) of mechanism to maximize overall metabolism.

 

[QuindariousGooch]

OK I'm going to do my best to explain PH since its something that is for the most part greatly misunderstood and can be confusing to new growers and even experienced growers alike. This will explain why we need both ppm and PH meters to give us informed information about PH

This will be a simple guide leaving out a lot of information. So lets get started with a couple of definitions to help you understand.

What is PH?

PH is a measurement of how alkaline or acid a solution is based on measuring hydrogen ions. It tells us nothing more than the ratio of acidic to alkaline elements. It does not tell us how much of each the solution contains or the alkalinity of the water.

What is alkalinity?

Alkalinity is the measurement of the waters buffering capacity (ability to neutralize acids). Its the total amount of carbonate and bicarbonate in the water that affects its ability to resist change to PH. If you know the alkalinity you can actually calculate the amount of acid of varying types needed to reach your target PH but we wont get into that.


So now we have a basic understanding of the difference lets get into some examples of source water and how alkalinity will affect PH.

RO and Distilled water

Ro and Distilled water is very low in mineral content containing carbonate or bicarbonate sources, we know this because if we test the ppm its usually under 40 and as low as 0ppm. This means it has a very low alkalinity (ability to neutralize acids) and is easily influenced by anything added that's acidic. But likewise it does not contain acid and is easily influenced by anything added that's basic. This results in a very unstable PH that can be easily influenced by anything added or anything its added to. In hydro the ideal ppm of carbonate/bicarbonate sources to provide an adequate buffer will be 50-100ppm with 75ppm being the target. Less than this and PH may swing to fast and be unstable, more and it will not drift enough and will require too much acid that could affect nutrient ratio's negatively depending on the acid used. By adding alkalinity and then acid we provide a more stable PH because adding more of either will have less impact on the overall ratio of acidic to basic elements

When used in hydro it should have alkalinity (a buffer) added back to prevent wild PH swings. Any source of carbonates, bicarbonates, silicates or hydroxides will work to create alkalinity. Sources i would recommend would be calcium carbonate, potassium bicarbonate (commonly sold as PH up) and finally what i would consider the best option is potassium silicate as it is a source of potassium and silica which are both excellent for cannabis. When using RO or distilled you will want to add back some calcium and magnesium if your nutrients are not designed for RO/distilled water as that's usually what Ro filters are removing for the majority. But most cal/mag is in the form of nitrate and provides no alkalinity (buffering capacity) so adding one of the previously mentioned or other is still a must.

When used in soil this unstable PH is actually IMO beneficial if you have a pre buffered soil (which you should) This means the water will have no impact on the PH potential (more on this later) of the soil and will almost instantly be influenced by the soil to the take on the PH of the soil makeup. This is why i feel we do not need to be PHing our nutrient solution for soil grows (unlike soiless and hydro). The soil is what will adjust the PH of our nutrient solution.

Tap Water

OK we all know tap water varies a lot form place to place and I will explain the basics of how to determine if your tap water is suitable or not for use. First we want the PPM and second we want the makeup of that ppm if available. Generally speaking the majority of the PPM makeup will be calcium carbonate. This is used to buffer the water supply and prevent acidic conditions that erode the coatings and will break down piping and leach them into the water supply such a lead (Flint Michigan ring a bell?) So we can generally assume the majority of the PPM in tap water is likely calcium carbonate but also some others like magnesium, sulfur, phospahte, iron etc. So if you have a ppm of 100-200ppm you can assume roughly 50-75% of that is calcium carbonate. Remember our target is 75ppm carbonate/bicarbonate sources to provide an ideal alkalinity (hope we are starting to see how import alkalinity is and we can't just go by PH) Now there are some cases when some sodium may be used such as sodium bicarbonate aka baking soda (can also be used as a buffer in a pinch but not recommended as a long term option) so we can google our local water report and see the makeup of the ppm in the water.

Soil PH potential

Now when we buy a prebufferd soil like most of the ones we use they come "Prebuffered" (alkalinity adjusted) what does this mean? This means the company has added amendments that when water is added the resulting PH of the water in the soil will be in a favorable range for growing our plants. Often times peat is used to lower PH and lime is used to raise PH in these soils. Just like in water we want to control the alkalinity (buffering capacity) of the soil to have a stable PH that is not easily influenced by adding things such as nutrients or other. Unlike hydro and soiless where we control the alkalinity (buffering capacity) of the water by adding it directly to the water it is applied to the soil. Which brings me back to my point of we don't need to PH our nutrient solution in soil because the soil provides the buffering and will adjust the PH. Now things like lime and peat break down slowly over time and only soluble elements will impact PH so this is how they control the PH in soil over long periods of time, because it breaks down slowly and only a small amount is soluble at a time its unlikely after a grow it has been depleted. But if we are reusing the soil we should be looking at re amending the buffering capacity before using again to ensure there is enough to last through the next grow. Often times farmers will do this once a year before seeding crops.

Effects of nutrients and source water on PH

First the PH down acids we use tend to break down much faster than the alkaline sources we use in both hydro and soil. For this reason we see a hydro systems PH generally rise over time unless something is creating more acid like decaying roots in which case we may actually see PH going down. Typically a PH increase of 0.2 in a 24 hr period is desirable and by adjusting the alkalinity we can control the PH drift. In the case of soil the acids used to bring PH down before feeding break down quickly and the alkaline and acidic buffer we have created minimizes the impact so they are really of not much benefit and have virtually no impact on long term PH potential of the soil. This is why we can't use them to lower high soil PH once we have an alkaline source buildup. However in hydro and coco PHing the nutrient solution is important because unlike soil there is not an adequate buffer established although in coco it is possible to do so.

Generally speaking the ratio's of nutrients we use will be acidic so when we get a buildup of nutrients we will almost always see PH drop. This is where you often hear ppl say flush the media. What this does is dilutes the dissolved elements and will remove some from the media in runoff.

Conversely a water source with high alkalinity can build up in the media and cause the PH potential of the soil to rise over time and in turn the PH of the water added to it. This is the reason we should look at the alkalinity of the water source not the PH as PH cannot measure the potential influence but rather only result.

Often in both circumstances its a good idea to flush the media to remove excess amount of available elements that may be affecting the PH negatively.

I'm gonna stop there and if anyone has questions i will do my best to answer them. If you have something you would like to add please do.


Aqua Man

Great post Aqua Man! The detail I avoided presented much better than I would have. Thanks for the time you put in. Well done Sir.
Q

 

[Moshmen]

Just reread the thread and makes more sense each time , if I read it enuff someday I’ll know it ! Lmao

 

[cemchris]

Yes, exactly, because the pH range is going to effectively be different rates at different sites within the soil itself. The top layer pH can have little to do with what's actually happening down around root level, especially if additives have been introduced, but also altered by the accumulation of inorganic salts, buildups and or waste products left behind from enzyme catalyzed reactions during the lifecycle of the plant. So, I think a living soil approach has it's big advantages in it's ability to "self regulate" the pH to some degree, and allows for a more natural (constellation) of mechanism to maximize overall metabolism.

How the Ammonium-nitrate ratio affects your plants | CANNA Gardening USA

In this article, we are going to look specifically at the effect of the ammonium/nitrate ratio and its effect on the growth and development. Read more >

www.cannagardening.com

 

[cemchris]

It also important to understand this for your wallet. Most off the shelf nutrients have plenty of everything as long as you select off back labels not front pictures. Most problems you see arise in your plants attributed to nutes, most of the time, is a result from feeding strength/medium content, temps/RH, PH, and watering frequency/amount. Getting a handle on those will save you from buying bottles of stuff or amendments you don't need. Short cut vs long cut per say.

 

[Flexnerb]

This is a great thread! Up until recently, I've overlooked "alkalinity" as pH above 7.0. What an "eye opener!" Funny how certain topics come up from different sources. The following video came out a couple days after the start of this post but they were dealing with the same topic. ALKALINITY.

A lot of growers have a pH and ppm meter but an alkalinity meter should be added to the list of recommended tools. Here is a nice, affordable one, the Hanna HI775. You can look it up or get one for a good price here.

HANNA ALKALINITY TESTER

DISCONTINUED THROUGH OCG 20% OFF REMAINING STOCK *No additional discounts Hanna Freshwater Alkalinity Colorimeter *Due To The Nature Of Water Testing Equipment All Sales Are Final. Warranty Handled Through Manufacture Stop wasting time struggling with a color chart. Get accurate water testing...

oregonsconstantgardener.com

Off thread topic: @Aqua Man, as a new soil grow experimenter, you might want to check out Nectar for the Gods. They use a "calcium driven" nutrient line that is different from the "salt" based nutrients.

I bought it..its very nice....my alk is 388ppm...ah, hell!!

Awesome for outdoor growers with multi plots and a local water source to feed from.

You'll only use it 3 to 4 times a year indoors!

I need a lot of acid to get mine down to 80ppm.

 

[Frankster]

How the Ammonium-nitrate ratio affects your plants | CANNA Gardening USA

In this article, we are going to look specifically at the effect of the ammonium/nitrate ratio and its effect on the growth and development. Read more >

www.cannagardening.com

It also important to understand this for your wallet. Most off the shelf nutrients have plenty of everything as long as you select off back labels not front pictures. Most problems you see arise in your plants attributed to nutes, most of the time, is a result from feeding strength/medium content, temps/RH, PH, and watering frequency/amount. Getting a handle on those will save you from buying bottles of stuff or amendments you don't need. Short cut vs long cut per say.

Bingo! There's so much crossover in so many amendments. Things like kelp for example, have a huge amount of trace compounds. These minerals and micronutrients need buffer to to allow the building blocks to be 'ready and waiting" for uptake. carbonates and calcium are critical components to these types of processes. The larger the buffering system, the more nutrients that can be lined up for absorption.

Carbon-concentrating mechanisms (CCM) is a remarkable adaptation, evolved to maximize photosynthetic efficiency of many photosynthetic organisms in low-CO2 levels of aqueous environment. (example: at root level)

In living animals, it's bone. Bones consist of living cells embedded in a mineralized organic matrix. Above 30% of the acellular part of bone consists of the organic components, and 70% of salts. Your bones also produce your, blood, marrow, (your cardiovascular fluids) which are at the very center of growth, cell maintence, immunity, oxygen transfer, and all the very processess that allow life to thrive on a cellular level. Your bones don't just stand you up, there a form of internal buffering mechanism. A "fluid" equilibrium structure. The the synthesis of bone mineral involves hydrolysis of an initial acidic calcium phosphate precipitate to octacalcium phosphate, which is then converted to octacalcium phosphate carbonate. You see it in shellfish, you see it in aquatic species, you see it in all living multicelluar organisms.

Carbonates play a huge roll in the development of any multicellular organisms, and in plants, it's all at the root level. The soil, or the hydroponic solution and it's Carbon-concentrating mechanisms plays a role similar bones, (or shells) in animals.

I suspect there's certain forms of carbonate that might be of benefit as an amendment, for buffering purpose.

 

[boomgagem]

@Aqua Man , I’ll have to read each link posted, but it was a great read so far.

Question: I’m on well water, 70ish ppm and I have a RO system with an alkalinity stage that’s supposed to add back minerals, comes out at 7ppm and closer to 8 pH.

I’m in Coco Loco (the amended stuff) and the whole fox farm line. I’ve been using my RO water and after adding all my nutes along with 7ml/gal cal-mag the pH is really acidic, so I’ve been using pH up to bring it back to 6pH. Should I not even bother using my RO system? I don’t have the numbers on my well water.

Im not having any issues other than I’m seeing a few brown spots on older leaves here and there.

 

[Aqua Man]

@Aqua Man , I’ll have to read each link posted, but it was a great read so far.

Question: I’m on well water, 70ish ppm and I have a RO system with an alkalinity stage that’s supposed to add back minerals, comes out at 7ppm and closer to 8 pH.

I’m in Coco Loco (the amended stuff) and the whole fox farm line. I’ve been using my RO water and after adding all my nutes along with 7ml/gal cal-mag the pH is really acidic, so I’ve been using pH up to bring it back to 6pH. Should I not even bother using my RO system? I don’t have the numbers on my well water.

Im not having any issues other than I’m seeing a few brown spots on older leaves here and there.

If your well water is 70ppm I would just use that.

IMPORTANT do not use any water that has gone through a water softener. It will almoat certainly kill your plants.

Being in soil and especially one like fox farm they are prebuffered. So personally I would not bother PHing your nutrients. My last soil grow I didn't PH once If the soil PH drops you can just add a tiny bit of dolomite lime to it. But it's highly unlikely.

 

[Aqua Man]

If your well water is 70ppm I would just use that.

IMPORTANT do not use any water that has gone through a water softener. It will almoat certainly kill your plants.

Being in soil and especially one like fox farm they are prebuffered. So personally I would not bother PHing your nutrients. My last soil grow I didn't PH once If the soil PH drops you can just add a tiny bit of dolomite lime to it. But it's highly unlikely.

Oh my bad I see you said coco... yeah you should be PH adjusting sorry for the confusion. I would also add some potassium silicate to help put some alkalinity into your water. For some reason I thought soil.

 

[boomgagem]

Ok cool, still use tap over the RO? I have the GH Armor SI I used in my last grow, will that be ok or should I order something better? The coco loco has been confusing. I was in straight coco last grow, but used this this time.

 

[Aqua Man]

Ok cool, still use tap over the RO? I have the GH Armor SI I used in my last grow, will that be ok or should I order something better? The coco loco has been confusing. I was in straight coco last grow, but used this this time.

Never used it. But I would PH for it. ArmorSI would absolutely work. ADD that forst then ph to 6.5 then add nutrients and adjust PH to what you desire to feed.

 

[Cracken]

aqua, you are a scholar and a gentleman. its always a pleasure reading your passed on wisdom. I will never remember all of what is in this thread but, the fact you take the time to type it out shows the type of person you are, and it can always be referenced in times of confusion.

 

[Aqua Man]

aqua, you are a scholar and a gentleman. its always a pleasure reading your passed on wisdom. I will never remember all of what is in this thread but, the fact you take the time to type it out shows the type of person you are, and it can always be referenced in times of confusion.

Appreciate the kind words bro.

 

[Frankster]

Just watched the video. Yeah RO can lead to depletion of carbonate/bicarbonate I made a comment somewhere back that was about building a soil that matches the source water. If using RO you may want/need to add some dolomite lime midway. If they are pre buffered it's usually not to much of an issue to make it through one grow (of course depending on source water and nutrients used) but it can be depending on pot size/volume and type of soil used. The other option is to add these directly to each feed but the use of ph down I think is poor practice in terms of controlling the ph of water in the soil. (Still may be needed for mixing the nutrients to prevent precipitate). An alkalinity meter would be a big asset in the tool box. In hydro 50-100ppm carbonate/bicarbonate. I feel ideally 75ppm for a decent drift but there are some other things that can have a small influence on this.

Someone else posted about soil I think it was 100-200ppm.

This is only carbonate and bicarbonate sources like calcium carbonate not the total ppm. Like I was saying in most tap water the majority makeup of ppm is usually calcium carbonate. So at 100-150 and even 200ppm should put you pretty close if it's city tap water.

Yes, this is all excellent information, thanks again Aqua Man. I've started using dolomite lime, but also I've tried to take it as far as possible. I've add tads of calcium carbonate, azomite, humics, dolomite lime, fossilized guano, and anything else that ancient organic sources of carbon. I want as wide and large deposit of buffer as possible, and trying to fit it into the smallest possible container, that's my goal. That way, I can keep tight control over the position of the plants during all stages of development, from seedling to finish, bumping them up to the appropriate size pro re nata

also trying to exploit, dial in all the chemical advantages of fluid dynamics. viscosity, surfactant, thermodynamics, and other physical properties that give way to well maintained metabolic needs and or preferences. Everything on a chemical level to assist in enhanced cellular function. there are no doubt, things to be learned from observing growth, and trying to quantify attribultes of the results.

Little things combined that magnify other bigger factors at play. Always pushing it further. It's like the Borg Omega Molecule. "perfection"



Janeway briefs her senior staff on the Omega molecule

"I won't risk half the quadrant to satisfy our curiosity. It's arrogant, and it's irresponsible. The final frontier has some boundaries that shouldn't be crossed, and we're looking at one."

 

[Frankster]

I'm not even gonna lie. I never knew there was an alkalinity meter!!! Thank you for posting this. I will be ordering one in the coming weeks to see how it works

I have heard of notg. This is my first and last soil grow probably for a while.

I think there's a ton of different test solutions also, it's for narrowing and cross referencing various ph ranges.
Also many indicators for various specific organic substances, or elements.

pH indicator solutions

Gentian violet (Methyl violet 10B)	yellow	0.0–2.0​	blue-violet
Leucomalachite green (first transition)	yellow	0.0–2.0​	green
Leucomalachite green (second transition)	green	11.6–14​	colorless
Thymol blue (first transition)	red	1.2–2.8​	yellow
Thymol blue (second transition)	yellow	8.0–9.6​	blue
Methyl yellow	red	2.9–4.0​	yellow
Bromophenol blue	yellow	3.0–4.6​	purple
Congo red	blue-violet	3.0–5.0​	red
Methyl orange	red	3.1–4.4​	orange
Bromocresol green	yellow	3.8–5.4​	blue
Methyl red	red	4.4–6.2​	yellow
Methyl red	red	4.5–5.2​	green
Azolitmin	red	4.5–8.3​	blue
Bromocresol purple	yellow	5.2–6.8​	purple
Bromothymol blue	yellow	6.0–7.6​	blue
Phenol red	yellow	6.4–8.0​	red
Neutral red	red	6.8–8.0​	yellow
Naphtholphthalein	colorless to reddish	7.3–8.7​	greenish to blue
Cresol Red	yellow	7.2–8.8​	reddish-purple
Phenolphthalein	colorless	8.3–10.0​	fuchsia
Thymolphthalein	colorless	9.3–10.5​	blue
Alizarine Yellow R	yellow	10.2–12.0​	red

 

[Rwhipple]

So we do not have to ph water if we grow in soil?

 

[Glassdub]

So we do not have to ph water if we grow in soil?

I do in containers, been told that it doesn't matter but if you keep pouring acid solution on a medium it will go acid eventually regardless of buffer, proved that positive last grow.

 

[Rwhipple]

I do in containers, been told that it doesn't matter but if you keep pouring acid solution on a medium it will go acid eventually regardless of buffer, proved that positive last grow.

What soil do you find is best so far. I've only ran with happy frog and sohum?