Quote Originally Posted by SnoopysGirl View Post
fill TA is 390. . . . .Should I at some point add muriatic acid?
Uh, wow. You'll be adding muriatic acid at some points, and some other points, and still some other points after that, with adding TA=390 water. With a 30K gallon pool, and that TA, you probably need to think in terms of 1/2 gallon doses, every time your pH exceeds 7.2, at least till your pool's TA is below 120 ppm. Just make it part of your routine.

But . . . read the muriatic acid guide linked in my signature.