Aqueon QuietFlow LED PRO Aquarium Power Filters Provides mechanical, chemical, biological filtration plus additional assistance with the Aqueon specialty filter pads Self-priming  starts up automatically after cleaning or power interruptions. Certified flow rates that assure proper water circulation for improved fish health LED indicator light flashes when its time to replace clogged cartridges by monitoring actual water levels. Internal pump design helps dampen noise and eliminate leaks Uses large Aqueon replacement cartridges