Thank you everyone for all the good information. I think I figured out what IMHO is, in my humble opioion? Is that right? I am not used to all the abbrev., but figuring them out, smile! I should ask our deaf daughter she texts all the time. Wow, I can't believe the sand last that long!! I know when we first got our pool the sand wasn't changed for 6-7 years, and when we spent oddles of money on chemicals, and water was still cloudy, they said it was the sand. Than it was clean the fliter sand. Of course that was with Baq. We were instructed to do a filter clean, filter aid, floc it, man!! Now you are saying don't clean the filter with any cleaners? Hmm! Interesting! Makes sense though if you have to clean it, flush it out, when you add chemicals it would tend to just gum it up.!