The Tetra Whisper internal aquarium filter is the ultimate in quiet, convenient 3-stage filtration. The dual-sided mesh of the Bio-Bag catches debris and fish waste while the activated carbon absorbs odors and discoloration. Biological filtration is provided by the Bio-Scrubber. Bio-Scrubber's anti-clog design provides complete biological filtration with the convenience of less maintenance. Because the Bio-Scrubber has a solid back, water is forced to flow evenly over the bacteria-rich bristles. The filter is submersible.