I'm beginning to wonder if the CYA level is somehow dropping more rapidly in pools in really hot climates like Texas. A friend of mine has been using pucks to chlorinate his pool for years. He does the standard weekly shocking treatment with some pool store product. Recently he had a very bad algae breakout and the pool turned green in a couple of days. All he evers measures is Chlorine level and PH. He didn't even know what CYA is. I figured I would use the opportunity to help educate him on the effects of high CYA. When I tested his pool, his CYA level was 60. This is a pool that is open year around with pucks used for sanitizing 24-7.
In my own pool in Houston, I use bleach primarily but also use pucks when I'm out of town. This spring my CYA level was low and I used a lot of pucks while my CYA level rose. However, it didn't rise nearly as fast as the Pool Calculator said. I bet I added 30 pucks over the course of the spring and my CYA rose about 20PPM.
Is there any information of other potential ways CYA could drop?