A power filter will do MUCH better than an undergravel filter. An undergravel filter sucks dirt and water through the gravel bed, resulting in a bunch of stuff stuck in the gravel. When you gravel vacuum, stuff will be vacuumed out, but the smaller particles are under the gravel filter plate. This will quickly build up and become a MESS. A power filter hangs on the back of the tank and will filter water with foam or floss media. The water is moved with an impeller inside a motor. Cleaning is relatively easy, take out the floss cartridge or the media basket (depending on design, most use floss cartridge, Hagen AquaClear uses a media basket) and clean it. The entire filter system can be taken off and cleaned as well.