I have finally gotten fed up with the filtration in my tank. I have a 55g tank with 1 red devil, 1 pleco, 1 catfish and 1 gold fish. My current filtration is an Under Gravel Filter and 2 Over the Back Filters. These OtB's seek to need cartidges replaced every 1 - 2 weeks. This is just gettin a little exhausting. What would be the best filtration I could possibly turn to? Perhaps a cannister, bio wheel or sump?