Quick question for water experts

K

KambleFrost

Active Member
So just a quick question.
Last night I mixed 70/30 RO water with tap water to get 150ppm
Mixed in Aloe Vera flakes in (1/8th tsp)
PH down to hit 6.1

today that simple water mixture is at 7.0 on the nose?
What the hell happen?
I thought tap water can raise but now I’m worried every feeding I do is wrong because it just bounces back to neutral...
Can anyone help?
Is it my ph down solution that sucks?
 
7CardBud

7CardBud

Well-Known Member
You should get a water report, my guess is your 150PPM contains good amounts of bicarbonate which is buffering the solution.
Try mixing your solution to pH 5.4 let it it sit 24 hours and then see where it buffers to.
 
Dank Bongula

Dank Bongula

Well-Known Member
Henry's Law...basically says the amount of a gas dissolved in water will work to be directly proportionate to the amount of that same gas in the air above the water.

So as your CO2 in the water off gasses, to reach equilibrium with the atmosphere above, your pH will rise...once it has reached equilibrium with the atmosphere above, it will stop and that will be your pH ceiling until you add something to force it higher or bring it back down.

Or your meter sucks bongsmilie
 
K

KambleFrost

Active Member
7CardBud said:
You should get a water report, my guess is your 150PPM contains good amounts of bicarbonate which is buffering the solution.
Try mixing your solution to pH 5.4 let it it sit 24 hours and then see where it buffers to.
Click to expand...
Is it good practice to mix nutrients a day or two before feeding then? And ph’ing just before feeding?
It’s 330ppm just 100% tap
I mix RO water with it to bring it to a 150ppm base water.
 
K

KambleFrost

Active Member
Dank Bongula said:
Henry's Law...basically says the amount of a gas dissolved in water will work to be directly proportionate to the amount of that same gas in the air above the water.

So as your CO2 in the water off gasses, to reach equilibrium with the atmosphere above, your pH will rise...once it has reached equilibrium with the atmosphere above, it will stop and that will be your pH ceiling until you add something to force it higher or bring it back down.

Or your meter sucks bongsmilie
Click to expand...
So in theory once the ph ceiling is hit if I bring down the ph with ph down will it still go back up to reach equilibrium? Or will it stay where I lower it to?
 
Lordhooha

Lordhooha

Well-Known Member
KambleFrost said:
So just a quick question.
Last night I mixed 70/30 RO water with tap water to get 150ppm
Mixed in Aloe Vera flakes in (1/8th tsp)
PH down to hit 6.1

today that simple water mixture is at 7.0 on the nose?
What the hell happen?
I thought tap water can raise but now I’m worried every feeding I do is wrong because it just bounces back to neutral...
Can anyone help?
Is it my ph down solution that sucks?
Click to expand...
Are you in soil or coco/hydro?
 
P

piratebug

Well-Known Member
The pH in water always naturally rises, water absorbs CO2 from the atmosphere, and it also releases CO2, through evaporation, into the atmosphere, when the water warms up, so the pH in any water source will sooner or later rise! And really the only time it won't rise is when you create stabilized solutions like pH calibration solutions with (sodium dihydrogen phosphate, disidium hydrogen phosphate, and potassium hydrogen phthalate) as those things block the waters ability to absorb and release CO2 in the water they are added to!
 
7CardBud

7CardBud

Well-Known Member
KambleFrost said:
Is it good practice to mix nutrients a day or two before feeding then? And ph’ing just before feeding?
It’s 330ppm just 100% tap
I mix RO water with it to bring it to a 150ppm base water.
Click to expand...
Your true pH is when the the gas exchange has reached equilibrium and the bicarbonate has had time to fully buffer.
You can never make a fully stable solution but being in the 5.7-6.3 range is fine since the promix also buffers.
Through trial and error you will find the right ratios to make your solution.
Then it won't matter when you mix it up since you know it will eventually settle in the needed range.

I also grow in Promix and had to find the right ratios for my well water.
Before I went into full production, I knew I wanted a 120ppm N feed and that would be 3.2 grams of Jacks per gallon.
I mixed up 5 gallons and ph'ed down to 5.5 knowing it would bounce back some. The next day I was at 6.3 so I pH'ed again down to 5.8.
The third day I checked and i had settled at 5.9 which is fine for my grow.

Now I know I can mix up a 33 gallon bucket with 95 grams of jacks and 12cc of pH down and be in the acceptable range every time.
I can use that water immediately or two days later.
 
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