my CH went from ~400 (for months) to 600 in less than a week. I added maybe 1.5" of water to get the level back up a bit, and removed the pool light from the niche, but beyond that I can't think of anything I've done recently (except remove the trichlor tabs, but that's been a few weeks). yesterday I did the test twice and quit both times because it wasn't changing color. today I decided to go and go and go and finally it changed at 60 drops. so my ta is too high and my ch is too high, of course I have the problems that can't be fixed without difficulty (i.e. aeration or replacing water but we're in a giant drought). anyhow, the main thing I'm wondering is how/why my calcium jumped so high. my first test was 400 on 5/2 or so, and like I said the pool store has been telling me 399 for a months. the water I added is the same water used to fill the pool in 12/2007 (new plaster). the only thing I can think of is if the house water softener recently ran? I don't even remember exactly what that does, but I think it has to do with sodium and calcium ions. my other numbers are below.