High PH help

[Jbthompson]

Hi there. I started using TFP last summer with my new pool and have learned so much. After having to drain to lower my CYA last summer, I am excited to get back at it. I have been adding chlorine etc all winter, and just did a baseline test. My PH was high (around 8) so I added 4 gallons of muriatic acid, and it lowered it to 7.2ish. Now about three days later, it is back around 8.0. Pool math is telling I need 39 gallons of acid, yikes. What am I missing here?

FC: 6.5
TA: 350
CYA: 60
PH: 7.8-8.
CH: 100

 

[mknauss]

Your pH will rise quickly with a TA of 350 ppm. I would suggest you carefully redo the TA test to confirm that number.

 

[mgtfp]

Just started typing, when I saw Marty's reply coming in. Spot on.

You mentioned that you had to drain and refill to lower your CYA. Might be worth to also check the TA of your fill water, high TA content in that would explain why the pool water has a high TA content. High TA means that there is a high amount of dissolved CO2 in the water. To reach equilibrium with the atmosphere, CO2 will out-gas from the water, which will increase pH.

 

[Jbthompson]

Ok will test TA again. Is there a way to lower it and the PH?

 

[mknauss]

TA - Further Reading

www.troublefreepool.com

Ok will test TA again. Is there a way to lower it and the PH?

 

[Jbthompson]

Tested it again, got 400. I tested it straight from my fill and it was 425

 

[mknauss]

OK -- well water?

Read the article I posted above. There is a process to lower your TA. Takes some effort but works well. It will take quite a bit of acid.

 

[Jbthompson]

Yes well water. Pool math says 39 gallons of acid. That will be pretty expensive. Should I put it all in at once?

 

[mknauss]

Yes well water. Pool math says 39 gallons of acid. That will be pretty expensive. Should I put it all in at once?

NO! Please read the article. You lower your pH to 7.2, aerate back to 7.6 or so, add acid, repeat, repeat, repeat.

 

[Jbthompson]

I have been adding acid about a gallon every other day. TA is currently at 225. I think I have put in about 20 gallons so far. I'm just concerned since my tap is highly alkaline when I have to add water this summer. Oh well.

 

[mgtfp]

Yep, once you have to start adding water, it will be a constant battle to keep TA from not rising too much. You'll hopefully get to some sort of equilibrium where the acid added for pH adjustments will keep the TA rise in check.