Regardless of how effective the filter is, periodic water changes and gravel cleaning is still a necessity
. No filter is powerful and efficient enough on its own to take care of all the needs of an aquarium, so bear that in mind and don't think that bigger is better, either. When in doubt, ask questions at the fish store and read the information on the filter boxes, and making the right choice should not be difficult. Buy the right size filter for the tank and do water changes, and your fish will stay happy and healthy!