Sand Filter Questions - Deep Cleaning but still not filtering well.

Jun 20, 2010
Liberty Lake,WA
I followed the deep cleaning a sand filter before I vacuumed all the winter gunk. Water came out clear. Cleaned/vacuumed the pool then deep cleaned the sand filter again since there was a lot of dirt on the bottom. I thought it would help but it didn't. After running the filter for several hours the fine dirt settled out again. Appears to be really fine if you look at it up close. I put in SeaClear to help before cleaning. Do I need new sand? or maybe some DE on top of the sand, or more sand?
I backwashed the filter in the fall before winterizing it. Water is really clear, just fine dirt on the bottom. Collects where there are expansion joints in the concrete pad under the pool.



Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
+1 what Tivo said. Unless you can pick up this "sand" between your thumb and finger and feel that it is gritty, it is not sand. The chances are you have a chemistry problem rather than a filtering problem.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Really fine dust that settles out in the same spots all the time, and which go *poof* as you approach with the vacuum is not dust. It's algae. Sometimes it clumps up like aquatic dust bunnies. It's not the filter's fault. You just need to kill it, then the filter can strain it out. We call the process SLAM Process