I had to start a SLAM last night (very discouraged about that, but that's for another thread). The manufacturer's specs for my fiberglass pool say that my pool capacity is 18K gallons, but the installer said that means when the pool is filled to the very brim, which (hopefully) never happens in real life. My pool is an irregular shape, so can't just do length x width.
I made a guesstimate and have been using 16K gal. in PoolMath. For my CYA (average of 3 tests was 65), PM said to add 420 oz. of 10% to get SLAM FC level, which is 26. I added 3-128 oz jugs and then measured the rest with a glass measuring cup.
Two hours later (~10 PM), I tested the FC and it was 32.5, not 26 (pump had been on whole time). I played around with PoolMath, and to get that level of FC, it says 12225 gallons! That would mean my pool was only about 2/3 full, which it clearly isn't.
I am confused.