I was gonig to ask the same question. I have been using PFS for years and never had a clouding issue. Not only in my tanks but this spring I just replaced the sand in my pool filter and it was very clean. By nature PFS has to be clean because it is used in pool filters. Playground sand, masonary sand, general purpose etc. however is very dirty and requires alot of rinsing before it is usable if either of these are not rinsed completly they can be disasterious cloud for weeks and containe quite a bit of silt. Did you but this at a pool store? I get mine at Leslie pools $10 for 50 lbs.