Koralia EVOLUTION 550 High Flow Power Head by Hydor. The Koralia Evolution 550 circulation pump offers the apex in efficiency and flow. Designed to work with wave timers, Koralia Evolution 550s also feature extremely low power consumption and superior energy efficiency. With a smaller footprint than previous models, Koralia Evolution 550 pumps blend seamlessly into your aquarium's backdrop. Koralia's patented magnet suction-cup technology is improved too: now featuring a vibration-absorbing element to minimize movement and support smoother flow. Specifications: * OVERALL DIMENSIONS: 6 in. x 6 in. dia. * MAXIMUM FLOW RATE: 550 gph * MAXIMUM TANK SIZE: Fresh - up to 90 gallon./ Salt - 50 gallon