Disapearing CYA


Active member
Jul 28, 2007
New Jersey
Hi all,

I've been a regular at the other site and learned a lot. I had a few years of great pool water but this year has been tough.

I'm having problems that my CYA is gone and I'm fighting algea which I now believe is due to no CYA.

I opened the pool to no CYA which I've had before and read this is normal. I used trichlor the first 2 weeks and got the CYA to 35 PPM ... great. Hadn't tested it again due to all the past years I tested it and it was always the same but I've been home the past few days and trying to kill the algea in the pool and been testing the chlorine every few hours and it's always close to 0. I was thinking that it's being used up killing something but today on a whim I checked the CYA and it was 0. I'm going to add CYA but I was wondering if anyone knew why I lost the CYA.

I have not filled and drained, although we had rain my pool didn't overflow too much (AG pool) but I did use some stain remover which was acid based and dropped the PH to 7.0 or lower and I used a lot of chlorine to neutralize it after 24 hours.

I'd appreciate any thoughts ... I also know now to test for CYA a few times a season.