I have a canister and a pump on my 180 with sand. When I do water changes I vac sometimes with the canister. Sometimes I get careless and suck up sand, it just sits in the bottom of the canister until I clean it out. My quiet one 6000 sits on the bottom of the tank with 2 inlets covered in floss. I can feel the sand in the floss sometimes when I clean it, but havent had a problem yet.