I slamned our pool, and changed filter sand went with a red sand from oklahoma, it came in 20 lb bags and 120 lbs of it is equivalent of 300 lbs of the white sand, also had bbs or fish weighys on bottom bu drain, once i could see with goggles on it was easier to get out the foreign debries. Filter had what appeared to be 2 inches of cotton on the top, and lots of green algie looking material in it as well. Slammed it for 2 weeks keeping the cfc up and got the majority cleared up. Still cant see the bottom but im going to slam it this week and i am sure it will clear up fast! On my second test kit, lol