To be honest, I never heard of CYA until I found this board a few weeks ago. I have no idea what it was at close, but I used the pucks in my chlorinator all last season, so it could have been high. I know I had a high chlorine demand last summer and I had algae growing in August. I really didn't know didly-squat about my pool and how to properly care for it before finding this forum, so didn't know how to kill the algae either. I think we used the copper algaecide before closing, but if I remember correctly, it was not clear when we closed it. The "pool guys" who closed it said it was not a problem. I think that all contributed to the big problem I had this spring.