I just changed the water in a 18/36 Vinyl IG pool with 18,000 gal capacity. It has a 1/2 hp pump; sand filter; and pentair 300 Chlorine 3" tab feeder. When I first tested after the refill FC: 0, PH 7.2 and A: 120,
I used the pool math to determine what I needed to add to the pool. I use...