During the spring I was stating my support for a program of mostly bleach or liquid chlorine most of the time and using Cal Hypo Shock on Sunday night after a long weekend of swimming. There were lots of Pros and Cons on for or against doing it that way...many people siding with FPM saying that I should not need to use the Cal Hypo...and others siding with me saying that if it was used once a week as a preventative, it was ok and what harm would it cause. Well I can honestly say that I have not used any Cal Hypo this year, and have only used bleach or as I am now using 12.5% liquid shock as it is called from The Great Escape...my local pool store. I have a much clearer pool and I have used nothing else. I have to say mom was right there really is no need to put the Cal Hypo in. As long as I maintain levels and test daily I am ok. Thanks FPM for setting me straight...One day I will learn never ever ever to question your knowledge again. ..Thanks for saving me the extra money!!!