Very helpful thread. I have an Aquarite SWCG and I have a PH of 7.4 and TA of 120 which I am able to maintain pretty consistently without adding acid. However I am reading alot in this thread about adding acid to maintain PH. Is this because most of these pools are plaster and not vinyl? I have an inground 12,000 gallon vinyl pool. Filter runs 12hrs a day and SWCG at 20%.