Why do you do this to me pH?

[bbdude]

Hi All - Happy Pool Opening Season!

Have learned a lot from this community since first getting a pool in 2022. However, my pH is a constant struggle especially through the winter close period. The pH shoots so high it creates scale. Here are the results of my final test before closing (before SLAM) and my first test 24 hours after opening and keeping the pump running. Any thoughts around what might be contributing to my pH shooting up during winter? Our winter was harsh too with almost 3 months with temps 32 or below.

Closing:
FC - 9
TA - 50
CYA - 70
pH - 7.8
CH - 350
Salt - 3400
CSI - (0.49)

Opening:
FC - 2
TA - 80
CYA - 30
pH - 8.2+ (it's the brightest magenta)
CH - 300
Salt - 2600
CSI - 0.14

I added a gallon of liquid chlorine this morning so I expect FC to bump up from 2 to 6.

 

[ajw22]

pH will rise to equilibrium with TA during the winter. Nothing you can do about that.

I have added 3 gallons of 31% acid to my 35K pool since opening and still don't have my pH in the 7's.

If you getting winter scale then add borates to your pool.

Borates in pool - Further Reading

www.troublefreepool.com

The Borate Pool Opening in Aqua Magazine discusses how borates can limit pH rise while a pool is closed for the winter. High pH while a pool is closed can cause scaling. Those that find their pools with very high pH at Spring opening may benefit from borates, with the pool open or closed.

 

[bbdude]

pH will rise to equilibrium with TA during the winter. Nothing you can do about that.

I have added 3 gallons of 31% acid to my 35K pool since openinga nd still don't have my pH in the 7's.

Thanks! Added Borates last year so I’m hopeful there isn’t a noticeable scale increase.

That’s a lot of MA! How much are you adding at a time?

 

[ajw22]

That’s a lot of MA! How much are you adding at a time?

1/2 gallon.

 

[bbdude]

1/2 gallon.

I was doing ~20oz at a time haha ... appreciate you chiming in with this. I started doing a 1/2 gallon every few hours and finally hit 7.8 this afternoon!

 

[ajw22]

I was doing ~20oz at a time haha ... appreciate you chiming in with this. I started doing a 1/2 gallon every few gallons and finally hit 7.8 this afternoon!

Maximum MA addition when pH is testing over 8.2 should drop your pH by 0.4 - 0.5. That keeps you safe from any one addition taking your pH below 7.0

 

[JamesW]

You can use PoolMath to calculate the amount of acid to use and it uses the TA and Borate to calculate.

As you can see, with Borates at 50 ppm, you can add about 3.76 times more acid in one dose without dropping below 7.2 pH.

PoolMath

Discover the calculator behind the perfect pool, PoolMath. Dealing with pools has allowed TFP to become the original authors of the best calculator on the net.

www.troublefreepool.com