Quote Originally Posted by Watermom View Post
The puzzling thing about this one is that even if she did have CYA bio-degradation over the winter, why doesn't she have a high CC reading?
She *has* had transient high CC levels. The thing you have to remember is that breakpoint chlorination -- so long taught in the pool industry -- actually WORKS, when the chloramines come from simple ammonia chlorine mixes. So, 'shocking' to eliminate chloramines can potentially do just that.