Alright, so we set up a cory cat specific tank about a month ago, to lessen the amount of fish my 15 gallon and to give the corys sand. It's ten gallons, and has a Topfin20 HOB filter and is heated to 76 degrees. It also has a java fern, and another plant I can't remember the name of, and a cave/rock and a clay pot. We let the tank run for about three weeks and put the corys in last week. They're all fine, but the filter gets kind of clogged kind of quickly, with the sand, and it's lowering the water flow. Would a canister work better? What can I do?