When I first received my TF100 test kit back around March or so, my CYA measured at about 70 to 80 PPM. I ended up draining a few inches of water from the pool in maybe April or May while vacuuming and refilled. My CYA tested at about 55 to 60 after that. A couple of months ago I measured my CYA at about 40. Just now, I did the CYA test twice and both times the water in the tube was crystal clear.
Last week, we had a nasty rain storm come through and as a result, my pump died. It took me 8 days to get a replacement pump and get everything plumbed in, so my pool was quite green. My pH has also been sitting a bit on the high side due to my lazyness for the last two months, maybe 7.8 or so.
Which would be more likely? 40ppm CYA gone in two months (with a week of no chlorine/circulation) and a water temperature of 90 deg F, or a bad reagent? The reagent has been stored in my kitchen on top of my refrigerator.
I'm reluctant to add CYA, but if it really is that low, then I guess I can finally use that 40 lb bucket of hockey pucks I bought less than a week before I found this site.