How much muriatic acid to add?

[waterbear]

What is your TA? if it is high it will make your pool resistant to pH changes. Keep putting in the acid and testing. It will start to move once it has overcome the buffer effect of your TA.
Post a full set of test results and we can get a better handle on what is happening in your pool. If you chlorine is not holding I wonder what your CYA level is.

[tundraSQ]

My pool is abotu 25k gallons and I needed to lower my PH in order to airate my water to bring my TA down. My PH was 7.8 and my TA was 160. I dumped a gallon of Muriatic acid in the pool last night by carefully pouring it so the return would spread it into the pool. This dropped my PH to 7.2 when I just measured it this morning. Of course after pouring in the entire gallon last night I read somethign where ben suggests NOT dropping it all at once...so in the future i will be adding it in 1qt doeses. Figuring each qt will provide about .15 drop in PH.