PH levels KEEP RISING....how do i stop this?

fatman7574 said:

Always adjust pH after each water top of at a minimum. Always top off you water every day. If you can afford it always use a pH controller so the pH never fluctuates beyond 0.05 pH points. pH is an much more important parameter to maintain than nutrient EC. All pH changes effect nutrient availability chemically, EC is only an indication of the amoun of electrical conductivity of the saly ts in the tank. Unless your EC is really low or really high EC really does not effect the plants ability to obtain its nutrient needs near as much as the pH efects that ability. Adding complete nutrients is not a safe way to adjust the pH. Phosphoric acid or Nitric acid for lowering the Ph or and Potassium hydroxide for raising the pH are safe methods.

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bran1981 said:

Hey fatman, would this be a good controller? http://www.marinedepot.com/ps_ViewItem.aspx?idProduct=AM1311&tab=1 Was also wondering how they accually adjust the ph, as in what does it use to adjust it?

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fatman7574 said:

Plants have different uptakes of nutrients at different time so with a mj formulation nutrient fertilizer containing principlally nitrate nirogen and less than 15% of its total nitrogen as ammonium nitrogen the ph is controlled by the nitrogen form that is atken up by the plants. During time of heavy vegative growth with good lighting the plants roots typically take up nearly all their nitrogen as nitrate. When a plant takes up Nitrate (NO3-) it releases bicarbonate (HCO3-), which increases the pH in thee nutrient reservoir. When the plant takes up Ammonium (NH4+), it releases a proton (H+) to the soil solution. THis increase of protons concentration which thereby decreases the pH of the nutriemt solution. With that large of a pH change it sounds like your experiencing heavy growt (nitrogen uptake) and have adeqaute enough lo ighting tat you are mainly taking up nitrate as your nitrogen. Hydroponic nutrients have very little buffering capacity because the solution is acid to begin with meaning there is a over abundance of H+ protons in the solution. This low pH means the only Alkaline buffers in the nutrients are bicarbarbonates. We can not add magnesium carbonates as a solid as they do not exist in a solid form. The only wat to get pottasium carbonate in th water is to have it form in the water. That means we need dissolved CO2 to form carbonic acid which then becomes a bicarbonate and then either a potatsium carbonate or a magnesium carbonate. Very little CO2 is in water and it is used up quickly in forming bicarbonates, so we can have very little potassium bicarbonate or magnesium carbonate in excess in our water at low a pH below 7.5. We can not add it to the reservoir in excess as we we are limited in what wecan have in the reservoir by the pH we maintain and the amount the water can hold at the low pH. If we add to much it just raise the pH above the desired 5.8 we usually shoot for. So when someone like Uncle Ben tells you to add magnesium bicarbonate or potasium bicarbonate ask them where they buy theirs. Some facts abouthydro just are unfixable. Buffering is pretty much an unfixable problem.

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dopeweed said:

Excellent description...just what I was looking for!
I understand then that adding nitric acid would be a sensible solution to drop the pH, too much phosphoric acid would upset the nitrate ratio. Am I on the right lines?

I also have some calcium chloride and magnesium sulphate. Could I use either of those to help buffering?

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churchhaze said:

None of those chemicals will really help to buffer the pH, except for phosphoric acid, which is a weak acid.

You can build a buffer using either a strong acid and weak base, or a weak acid and a strong base.

Phosphoric acid + potassium hydroxide is one of the only viable buffers that can be effectively used in hydro. Monopotassium phosphate by itself also has decent buffering capacity because it still has another H to be dissociated.

H3PO4 would become KH2PO4, then KHPO4.

Carbonate buffers are another, but carbonate levels can not be too high, so buffering capacity potential is limited.

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dopeweed said:

Thanks for reply! I have both of the these chemicals. I'm suffering from a huge ph increase due to (possibly due to bacterial action after a fungus gnat infestation and cannazym breaking roots down).

If the the ph is going up, due to nitrates being taken up, even tho it might be possible to buffer using these chemicals it may be worth keeping an eye on it in order to provide the additional nitrates required.

Thanks again for such an informative and useful reply!

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fatman7574 said:

Always adjust pH after each water top of at a minimum. Always top off you water every day. If you can afford it always use a pH controller so the pH never fluctuates beyond 0.05 pH points. pH is an much more important parameter to maintain than nutrient EC. All pH changes effect nutrient availability chemically, EC is only an indication of the amoun of electrical conductivity of the saly ts in the tank. Unless your EC is really low or really high EC really does not effect the plants ability to obtain its nutrient needs near as much as the pH efects that ability. Adding complete nutrients is not a safe way to adjust the pH. Phosphoric acid or Nitric acid for lowering the Ph or and Potassium hydroxide for raising the pH are safe methods.

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snutter said:

this is NOT correct.

In a healthy hydro system, the pH should not be "jumping" up each day as you mention. And you most definitely should not have to be adding pH down every day. In fact, you really don't want to have to much pH down in your nutrient solution if possible.

Now, to figure out your problem we need to know a little bit more here:

What type of nutes are you using? What's your ppm?

How far along are your plants?

what type of hydro system did you build?

what is your growing medium? (this is an important question. For example, if you're using rock wool, and running a drip system, then this can cause your pH to rise. The reason it can is because rock wool has a high pH, so dripping through it can cause your nutrient solution's pH to rise).

what type of water are you using (e.g. RO, distilled, tap, etc.)?

This should be a good start. I'll try to keep an eye on this thread and watch for your answers.

-S

PS
I run a DWC hydro system. I use 18 gallon totes, with 12 gallons of nutrient solution. When I mix up a fresh batch of nutes, i of course adjust my pH. This is the ONLY time I need to adjust. In general, it stays right at 5.5 until the next nute change.

which brings me to my other point, someone mentioned a pH of 6.2 for you. That's incorrect as well. That's pH for soil. For hydro you want to stay in the realm of 5.3 to 5.8, no higher no lower...

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HydroRed said:

Best advice I can give is run your ph a tad lower with the expectation of it rising if you know its going to creep up. This creates a "swing" allowing the plant to hit the perfect range for every nutrient and mineral across the board as it swings up. Example: You set your ph to 5.2 then over the next 4-5 days it creeps up to 6.0 - 6.3 you have effectively crated the ideal ph for nutrient uptake for every basic and essential nutrient & mineral in hydroponics. Once the ph hits 6.0 - 6.3 after 4-5 days (or however long yours takes), adjust it back down to a 5.2 ph & do it all over again. Me being a visual kinda guy, I attached a chart to help anyone who might not understand why this is a useful practice in hydroponics.
View attachment 3618784

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jimmy311 said:

That's what i do but it climbs fast?

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bdt1981 said:

You know i dont have tons of expirence with hydro, 2010-2013 ebb and flo, just picked back upwith an aeroflo2 36. And seems like the ph always went up. I know today it is raising fast like drop to 5.8 and by next day its at 6.2ish i dont really hit it with down until 6.5 then back to 5.8 to wait til it gets back up.
I dont know if i ever have saw a stable ph for long. I also dont see any deficiencies with the plants. I guess there could be alge but i dont see any. I didnt complely drain my res when i changed nutes. Less than a half gallon of old nutes remain in the bottom and to much trouble getting it all.
Hard to believe the guy who uses 16gallons of nutrient and only adjusts the ph 1 time and it stays there... real hard, like almost borderline bullshit. But i cant know for sure so i wont say anything..
More root the faster the ph rises in my expirence.

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bdt1981 said:

You know i dont have tons of expirence with hydro, 2010-2013 ebb and flo, just picked back upwith an aeroflo2 36. And seems like the ph always went up. I know today it is raising fast like drop to 5.8 and by next day its at 6.2ish i dont really hit it with down until 6.5 then back to 5.8 to wait til it gets back up.
I dont know if i ever have saw a stable ph for long. I also dont see any deficiencies with the plants. I guess there could be alge but i dont see any. I didnt complely drain my res when i changed nutes. Less than a half gallon of old nutes remain in the bottom and to much trouble getting it all.
Hard to believe the guy who uses 16gallons of nutrient and only adjusts the ph 1 time and it stays there... real hard, like almost borderline bullshit. But i cant know for sure so i wont say anything..
More root the faster the ph rises in my expirence.

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Delo said:

well i made my hydro system. looks nice and good. but every day the PH level jumps up and i gotta keep adding more PH down to level it out. anyone know why this keeps happening? and how to make it stop?

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