I had 11 fresh water tanks at one point all with sand blasting sand from TSC, very cheap. Easy to clean cause nothing fell past the surface. Only problem I found was if the fish, while digging, spit the sand out near the filter inlet the sand would ruin the impellar of your pump. To cure this I put a pre filter on the inlet made of a small pc of sponge. Once I did that I never had a problem again, just rince out the pre filter on a regular basis