The PRO 3e is the world's first microprocessor controlled aquarium filter, and it comes equipped with an assortment of advanced and innovative features. The Constant Flow feature monitors increased blockage and automatically compensates to maintain your settings. This guarantees constant through-flow and long intervals between cleaning. The electronic Output Control allows you to determine your preferred flow setting based on the requirements of your aquarium (from minimal output to maximum boost), and the Stream Function creates a wave-like effect by continuously alternating the flow rate to simulate living conditions of a variety of freshwater and saltwater fish. Other features include a 12-Hour Bio Function, which changes flow rates every 12 hours to simulate day/night cycles, and an Electronic Air Indicator that performs a variety of diagnostics on your filter and makes automatic corrections. All together, this high-tech, high performance filter will make a welcome asset to any freshwater or saltwater aquarium. (Suitable for aquariums up to 185 gallons and produces a 490 g/h output).