The Penguin 350B Bio-Wheel Power Filter provides superior biological filtration for freshwater or marine aquariums. The Bio-Wheel is the ideal culture site for the growth of beneficial bacteria. This filter requires no pumps, valves or tubing and the Bio-Wheel will never clog or need replacing. The Penguin provides 3 stage filtration: Stage one-mechanical filtration-the filter cartridge filters dirt and debris. Stage 2-chemical filtration-Black Diamond Carbon removes odors and discoloration. Stage 3-Biological filtration-Bio-Wheel eliminates ammonia and nitrite and is the ideal place for the growth of beneficial bacteria. Also features: larger Bio-Wheel, filter cartridge, noise reducing cover and adjustable mid-level intake. Filters 350 gph and is good for tanks up to 75 gallons in size.