Whisper Power Filters are quiet and have reliable three stage filtration. Stage one, mechanical filtration with a dual sided mesh bio-bag that catches debris and fish waste. Satge two, chemical filtration with ultra-activated carbon to absorb odors and discoloration. Stage three, Biological filtration, where the bio-foam creates a large 3-dimensional area for cultivating aerobic bacteria, which eliminates toxic ammonia and nitrites. Use a Whisper Power Filter for a crystal clear aquarium.