I can't really recommend canisters on a reef system. If they are not cleaned weekly, they become oxygen consumers and nitrate factories. If you got to have something in this area, the Vortex Diatom filter, suggested by Witfull is your best choice for mucking out the tank bottom on a weekly basis. (You use a Vortex Diatom filter only part time)
A better question might be "What is the best way to keep my bare bottom reef tank clean?"
To do that I'd use a closed loop with the output of the loop going to a spraybar length of pvc pipe run along the middle of the tank bottom. This would create a constant flow of water across the bottom, keepint it clean.