corrected ph, after a few days, back to same level?

Apr 22, 2017
21
Southern Indiana
recent full test results were

fc 5
cc 0
cya 30
ph 7.8
ta 90
ch - vinyl, dont test

Last week I decided to tweak cya slightly to bring it up to 40 and bring ph down a bit to 7.4.

after cya was done dissolving, I waited a day, then added muriatic acid and tested ok at 7.5 (prob water volume is wrong)

A few days later, ph creeps back to 7.8 but stays there. Has never tested at 8. I added no fill water, I have no water feature. It's manually chlorinated. I added no chemicals besides 12.5 % bleach daily.




is 7.8 a big deal? I wanted it to be mid range rather than at the top. Any other reasons why it may be creeping back up and staying there and can I try anything else?
 
It's creeping up because that's what pH does. Part of it is the TA. Each time you lower pH, you'll lower TA a little, and so the amount of acid needed to make a change will go down and the intervals between additions will get longer.

Question: why do you want pH to be midrange?

Anything between 7.2 and 7.8 is fine for swimming. I personally like to target 7.2 when I add acid just so I can go longer between additions.

Why don't you test CH? You have the reagents. Low CH is no problem, but high CH can still lead to scaling. I'd want to know what mine was even if it didn't need any attention.
 
I would probably leave it alone but lowering TA only with muriatic will not work. There is a process in Pool School that will teach you how to acid/aerate to lower TA on a more permanent basis.
 
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