Rising pH in res used for handwatering?

Cwmoore577

Cwmoore577

Well-Known Member
I’m not growing in a hydro setup but didn’t know where else to ask this question.

I have two plants currently in coco that I’m handwatering 3x daily. So instead of mixing, ph’ing and measuring my nutrients in a gallon jug 3 times every day I’m trying to make a “res”.
I’m using a plastic tub, and an air pump/air stone that I picked up from the sporting goods store.

I pour 5 gallons of tap water in, mix my calmag first, then my veg nutrient, and then pH it to 5.4-5.5 as it rises pretty quickly. Within 10-15 minutes it will be at 5.8. By next day it will be around 6.5-7.5. Is this normal? Is there anyway to stabilize it or do I just have to keep pH’ing it every time I water?

And should my air pump run 24/7?

I use Emerald Forest CalMag and General Organics BioThrive Grow.
 
Renfro

Renfro

Well-Known Member
An air pump is typically associated with a pH drop as the bubbles contain CO2 and that makes carbonic acid. That said the tap water is overwhelming that and your pH is rising.

The solution is to use RO water and a submersible pump for circulation while mixing your nutes while adding them to the water and for oxygenation. You could set the pump on a repeat cycle timer to run for like 1 minute every 10 minutes or 15 minutes to avoid heating the water up causing it to hold less oxygen. Doing those things my tanks on nutes will stay stable for weeks once pH'd.
 
Renfro

Renfro

Well-Known Member
The other solution is to use a pH dosing pump system to keep the pH down or just pH every time you water.
 
Cwmoore577

Cwmoore577

Well-Known Member
Renfro said:
The other solution is to use a pH dosing pump system to keep the pH down or just pH every time you water.
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Ok I wondered if it was my tap water or the nutrient line I use not being made for hydroponics. I’ll try switching to RO and see if that helps.

And so it would not be harmful to keep using more pH down in the meantime?
 
Renfro

Renfro

Well-Known Member
I have 30 and 55 gallon drums as my reservoirs for hand feeding. Despite a stable pH I generally only pH the whole drum if I am going to use the whole drum right then, otherwise I just mix the nutes in the drum and pH the buckets as I pull them off.
 
kingromano

kingromano

Well-Known Member
when i do my reservoir, i always prepare it the day before .. i mix the nutrient wait 15 minutes for the chemical reactions to stabilize, then i set the ph
but i know that the next morning it will be way higher .. its absolutely normal
then i set it again.. and after that it must stay stable
but of course if you use a pump to mix it constantly after that it will aerate the solution which will make it climb ( a little)
 
A

Aqua Man

Well-Known Member
GH PH down is a mix of phosphoric and nitric acid i believe. My guess then would be you have a low carbonate/bicarbonate water source which make the PH unstable. This is what provides the stability to PH. So the amount of acid being added is inadequate. The more buffer in the water and more acid used to bring it down creates a more stable PH. Now this is not to say adding a shit ton of each and doing so wil provide a stable PH it will cause other issues. My suggestion is add a 1/2 tsp baking soda (not powder) per 5gal to the water then add your nutrients then PH down.
 
A

Aqua Man

Well-Known Member
Also tap water ph IME rises after being left out. The reason being it's in a closed system and under pressure so small amount of organics that react with the chlorine/chloramines give off CO2 because of the pressure the CO2 is immediately absorbed into the water and forms carbonic acid. Depending on the amount of carbonate and bicarbonate this will have a varying affect but will generally lower ph. If the carbonate and bicarbonate is high it may remain stable. Generally water supplies use calcium carbonate to keep ph up over 6.8? I think. As acidic water can erode coating and heavy metals in pipes... Remember flint?

Long story short it's best to bubble your water before phing this helps the water reach equilibrium with the air and helps ensure a reliable ph reading free from influence of extra carbonic acid in tap water
 
Cwmoore577

Cwmoore577

Well-Known Member
Aqua Man said:
Also tap water ph IME rises after being left out. The reason being it's in a closed system and under pressure so small amount of organics that react with the chlorine/chloramines give off CO2 because of the pressure the CO2 is immediately absorbed into the water and forms carbonic acid. Depending on the amount of carbonate and bicarbonate this will have a varying affect but will generally lower ph. If the carbonate and bicarbonate is high it may remain stable. Generally water supplies use calcium carbonate to keep ph up over 6.8? I think. As acidic water can erode coating and heavy metals in pipes... Remember flint?

Long story short it's best to bubble your water before phing this helps the water reach equilibrium with the air and helps ensure a reliable ph reading free from influence of extra carbonic acid in tap water
Click to expand...
Ok so like Ren said, mix my nutrients with the water and only pH after I’ve taken it from the res into my gallon jugs?

Thanks for the info guys, always it’s good to know why it’s happening and not just what is happening.
 
Wastei

Wastei

Well-Known Member
I would drop the organics if you want a pH stable solution. You could try mixing potassium silicate before adding nutrients to buffer the water and stabilize the solution. The nutrient solution will change pH value in the containers either way just as in the reservoir.

Or just don't bother to pH your nutrient solution and add some myko product (Great white for example) to your containers. You don't really need to pH organic nutrients with living cultures.
 
A

Aqua Man

Well-Known Member
rkymtnman said:
does GO recommend bubbling organic nutes? that could be the problem
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The desirable bacteria that breaks down organics are aerobic. So if anything bubbling will aid in thier use. People who make teas bubble them for this specific reason the high amount bacteria can deplete it of oxygen very quickly if left stagnant killing off your bacterial culture.
 
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