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PH Drift

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PH Drift

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#1
For years I've wondered wtf, more often than not when I mix a batch of nutes in the mixing barrel and set the ph if I don't use it all at once, by the next day the ph will be off. I always figured it was due to a temp difference but I recently read up about it and my bluelab meter adjusts for temp. Any Bill Nye types know whats going on here? I'm starting to wonder if up/down products aren't all created equal.
 
#2
Depending on what stuff you mix together, it can react in the tank and change the Ph. Water's Ph changes as it sits from CO2 and stuff, and those small changes can cause some nutrients to either precipitate out of solution or change forms. Calcium and Phosphorus can combine, over time, to creat Calcium Phosphate, which raises Ph I believe. The change fo that Ph can cause even more issues... there is a certain way that the mixing of nutrients and stuff should be done. I think the Ph adjustment is the last thing to do before using the brew.
 
#4
All of the above. Especially sources and as mimed pointed out aeration and surface area.

Take citric acid it degrades very quickly and in most systems with good gas exchange will be virtually depleted in around 12 hours IME. The ph drift is a balancing act. The more alkalinity the more acid needed to lower the ph but also the more stable the ph. Finding that balance to give a 0.2-0.3ph drift is the key. If you make the ph rock stable it can affect nutrient uptake and is more likely to be overall unbalanced.

Tap water for example has chorine/chloramine that react with organics producing CO2 and other in a pressurized system that does not allow the CO2 to offgas and produces carbonic acid lowering the ph. When it comes out of the tap and is aerated the ph will rise as the excess CO2 produced from those reactions are off gassed. This is why it's always best to aerate your source water and system to improve stability
 
#5
Depending on the system I would say mix your nutrients but only ph down to the desired ph before feeding. Also sulfuric and phosphoric acid are way more stable than say nitric or citric acid and will hold the ph down longer. But starting with good alkalinity is key
 
#7
Appreciate it guys. I understood some of that.🙂 I'm back to using House & Garden, years back they used to recommend letting the part A gurgle for 10 mins or so, one of their reps told me they dropped that but I still do it for OCD reasons. I also put my calmag in early too for some magical reason I don't understand.

It sounds like it's normalish I always reset the ph if I use it the next day. I mostly wanted to make sure that my brand of ph up/down wasn't artificially or just temporarily doing its job.
 
#8
3 balls said:
Appreciate it guys. I understood some of that.🙂 I'm back to using House & Garden, years back they used to recommend letting the part A gurgle for 10 mins or so, one of their reps told me they dropped that but I still do it for OCD reasons. I also put my calmag in early too for some magical reason I don't understand.

It sounds like it's normalish I always reset the ph if I use it the next day. I mostly wanted to make sure that my brand of ph up/down wasn't artificially or just temporarily doing its job.
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look at the ingredients
 
#10
3 balls said:
Mad Farmer Get Down
phosphoric acid
citric acid
ammonium sulfate

Mad Farmer Get Up
potassium carbonate
potassium silicate
potassium hydroxide
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Ph up is good. Ph down I just use 85% phosphoric acid
 
#12
BillFarthing said:
Citric acid is a weak acid and is used as a carbonate buffer in pH down.
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All acid is used to buffer carbonate in ph down. I agree citric acid is weak and a poor choice for hydro. It also very cheap and why I believe they use it as a filler. Straight phosphoric or sulfuric acid is much better. At higher concentrations like I use at 85% I suggest diluting 10-1 before use
 
#13
Aqua Man said:
All acid is used to buffer carbonate in ph down. I agree citric acid is weak and a poor choice for hydro. It also very cheap and why I believe they use it as a filler. Straight phosphoric or sulfuric acid is much better. At higher concentrations like I use at 85% I suggest diluting 10-1 before use
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I have read that including multiple forms of acid is better ph down.
 
#15
Aqua Man said:
What's the advantage? I can see to spread the sources out but can't see any functional benefit other than that.
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I dont know but most of the ph adjuster brands use multiple sources. And when i learned about it i read that.

Maybe better stability? I would have to re search for answers.
 
#16
MIMedGrower said:
I dont know but most of the ph adjuster brands use multiple sources. And when i learned about it i read that.

Maybe better stability? I would have to re search for answers.
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I can't see stability. Unless they are trying to claim that nutrient uptake may interfere with source of acid but IME that holds no water and may be just another marketing gimmick to fill with cheaper acid. Source should be taken into account but if you have the right alkalinity to start with you should not need so much that it interferes. If any blend I would do sulfuric and phosphoric. Nitric and citric would have very specific uses for a very dialed in grow. Citric imo should never be used unless your not getting enough drift but that's a very specific use.
 
#17
Aqua Man said:
I can't see stability. Unless they are trying to claim that nutrient uptake may interfere with source of acid but IME that holds no water and may be just another marketing gimmick to fill with cheaper acid. Source should be taken into account but if you have the right alkalinity to start with you should not need so much that it interferes.
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I disagree. Different acids have different composition and break down at different rates. Maybe longer lasting stability from multiple sources.

But im just guessing still.
 
#18
MIMedGrower said:
I disagree. Different acids have different composition and break down at different rates. Maybe longer lasting stability from multiple sources.

But im just guessing still.
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Doesn't work that way afaik. I don't believe one acid will affect the stability of another.

@cemchris may have a good handle on this. To my knowledge atleast it doesn't affect stability but rather a blend would be a cost cutting solution while still providing an adequate product.

The only way I can see any impact is nutrient uptake like stretch where the plants can be a phosphorus hog.
 
#19
Aqua Man said:
Doesn't work that way afaik. I don't believe one acid will affect the stability of another.

@cemchris may have a good handle on this. To my knowledge atleast it doesn't affect stability but rather a blend would be a cost cutting solution while still providing an adequate product.

The only way I can see any impact is nutrient uptake like stretch where the plants can be a phosphorus hog.
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Not one acid stabilizing another. Different acids affecting alkalinity differently. Like calcitic and dolomite lime for long and short term ph control.
 
#20
MIMedGrower said:
Not one acid stabilizing another. Different acids affecting alkalinity differently. Like calcitic and dolomite lime for long and short term ph control.
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Yes that what I mean citric breaks down in about 12hrs IME in a well aerated system. I have never seen a hydro grower with the issue of ph not drifting but I have seen numerous ph drifting to much (instability) so for our use we don't have the issue of short and long term. Just the issue of ph drifting to fast. Which will be 1 of 2 things. Weak acid ph down like citric... Or inadequate buffer to start with creating stability issues. Because of lack of buffering. Basically you can't add enough acid to keep it stable without a ph crash or extremely low ph
 
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