Refresh your finned friends’ abode with the Marineland Penguin PRO 125 Power Filter! Featuring a three-stage mechanical, chemical and biological filtration system, this cutting-edge filter cycles through your 20-gallon aquarium six times per hour with flow control up to 125 GPH ...Refresh your finned friends’ abode with the Marineland Penguin PRO 125 Power Filter! Featuring a three-stage mechanical, chemical and biological filtration system, this cutting-edge filter cycles through your 20-gallon aquarium six times per hour with flow control up to 125 GPH. It even contains BIO-wheel technology, which nitrifies bacteria growth and eradicates toxic ammonia and nitrate. Plus, this filter is ultra-quiet thanks to a decoupled motor, allowing you to relax and enjoy your awesome aquarium.