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 content for healthier, more active fish. There are five total stages of filtrationmechanical, chemical, biological and an additional specialty padfor the cleanest, clearest, healthiest water. Stage 1 Dense floss removes particles and debris. Stage 2 Activated carbon removes toxins, odors and discoloration. Stage 3 Patented Bio-Holster removes toxic ammonia and nitrites. Stage 4 Diffuser grid removes additional toxins while adding oxygen for more active fish. It also reduces splashing makes the return exceptionally quiet. Stage 5 Specialty filter pad option for additional carbon, ammonia reducer or phosphate remover. All filters use Aqueon Replacement Filter Cartridges and Aqueon Specialty Filter Pads. QuietFlow LED Pro 10 Medium cartridge, QuietFlow LED Pro 20, 30 and 50 Large cartridge, QuietFlow LED Pro 75 two Large cartridges.