Quote Originally Posted by apoolman
the only way to reduce this level is to drain water off the top of the pool and replace with fresh water. .... CYA stays at the top 3 inches of the surface of the pool on a calm steady day. Draining from a skimmer or a scum ledge is the best way to lower CYA if it gets too high.
That is the first time I’ve heard that. Any studies/documentation that backs this up? If this is true, it would make lowering CYA much easier. Sorry to be skeptical but sounds way too good to be true. Chemistry was a long time ago so hopefully I'm wrong in my un substantiated doubt, I HOPE!.