Aqueon QuietFlow LED PRO Aquarium Power Filter 20 ( Up to 30 gal)Featured is a LED filter cartridge change indicator light that flashes when the cartridge becomes clogged with debris, providing a reminder that it's time to replace the cartridge. A great benefit of the Aqueon QuietFlow filters is the internal pump design that helps dampen noise, eliminates leaks and because it is self priming, starts up automatically after cleaning or power interruptions. Higher flow rates also ensure a higher dissolved oxygen