I have a tank with sand on the bottom. I recently put 2 aquaclear 110s on it with prefilters. I did that because I had heard the aquaclears didn't do well with sand. After 14 hours then prefilters were so dirty water was barely trickling out of the filters so I took the prefilters off. They seem to be doing fine. I saw one had a little sand setting in it. I'm using play sand. It's a 210 gallon aquarium with 2 aquaclear 110s, a rena xp4, hydro v connected to a powerhead, and an fx5 so I think I have plenty of filtration. I don't know why they got ditty so fast. I put the aquaclear 110s on though because I got tired of cleaning the canisters every week or two. Right now I have 2 spotted raphael catfish about 2.5 inches, 2 pacus 7 inches, 2 oscars 7 inches, 1 jack dempsey 4 inches, 2 green terrors 3 inches, 1 green sunfish 5 inches, 3 midas and 2 red devils 4 to 5 inches, 1 pleco 8 inches, 1 gold gourami 4 inches and 1 green texas 3 inches. I know those won't all work together in that tank in the future and the pacus will be too big. I'm going to get a bigger tank and move fish around eventually. Im curious if I need more filtration with that stocking level since the filters seem to dirty up pretty quickly and if I need prefilters on the aquaclears. I have an Eheim 2080 on a 54 gallon corner aquarium I could trade out with the xp4 probably. Thanks.