- Jun 22, 2014
- 48,695
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Okay Amy ... well for simple math, we can expect that a 50% drain will lower your CYA to 60. That's not bad at all. I actually keep mine that high because of the intense sun. If you are comfortable draining that much at once, that's the best option. Knockout the water exchange and then you can resume normal chemical adjustments. Good thing is once the CYA is lowered, it will never go up again unless YOU want it to. If you have any more questions about the CYA or drain let us know.