Well last year my CYA was way high (can't remember what) and I was continually having to shock to get rid of algae. This year it is down but I am still having bouts of algae. I started using pucks again in my floater to boost the CYA a little but I am afraid to let the chlorine drop below 5 because that's when I seem to get the algae. I think I'm confused about now.