Not 100% sure of the CYA. I wish there was a better way to test than the black dot. it is so hard to be sure. Does water temp and hot weather affect the rate of chlorine burn or just uv? I am wondering if it could just be high because the heat wave we have had. I would hate to bump the CYA if at all possible. Wondering if the weather cooled off a little or had a day with some clouds if it would slow down. Also was wondering if the bond between CYA and chlorine was instant? i guess i am wondering if it might need a little extra for a few nights for the stabilizer have enough to do its job then it might slow in a few days? I would think it would be fairly quick but I don't really know enough about this yet.