my bad should be 24'x52" sounds like 13000 or 13595 gal depending on where you look

The PH I have been told is 9.1 to 9.2 out of the tap and remains consistent. Per local water company. So I will need to lower. Looks like several choices are available for this. I was under the impression that it is hard to maintain the Chlorine levels until the PH is where it should be. Did I misread that?