The Whisper 30 Power Filter provides quiet and reliable aquarium filtration for clear and healthy aquarium water. The Whisper 20 Filter provides mechanical, chemical and biological filtration for both freshwater and saltwater aquariums up to 30 gallons. It is economical and easy to use. The Whisper Filter provides mechanical aquarium filtration with a dual-sided mesh that catches debris and fish waste in its dense fibrous network. Chemical filtration is achieved with Ultra-activated carbon that absorbs odors and discoloration from your aquarium's water. The Aerobic Frame is deeply etched to provide a receptive surface for aerobic bacteria for biological aquarium filtration. Using the same Aerobic Frame and replacing only the carbon and the mesh helps to maintain biological filtration in the aquarium. Aerobic biological filtration converts toxic ammonia and nitrites into less harmful nitrates. The aquarium filter has a convenient flow control knob that allows you to turn down the flow to promote better fish feeding. It also extends filter cartridge life by reducing uneaten fish food particles that can cause clogging. Both chemical and mechanical aquarium filtration are accomplished by easy-to-use Whisper Filter Cartridges. These Bio Bag filter cartridges contain both the mesh pad and the carbon filter media required for aquarium filtration. Biological filtration takes place on the Aerobic Frame on a seperate filter pad. The Whisper 30's energizer is 7 watts. Includes 6 1/2" main tube with magnet impeller assembly, 5 3/4" strainer, one Bio Bag Whisper Filter Cartridge and Aerobic Frame with Bio Foam.