Tetra Whisper 10-30 Internal Filter for aquariums is the ultimate in quiet, convenient 3-stage filtration. This submersible filter mounts on the inside of the aquarium, rather than hanging from the outside, making it possible to place the tank flush against a wall and easily hide with tank decor. The air pump (included) provides bubbles that move water through the filter, efficiently filtering and oxygenating your aquarium. The water flows through Ultra-Activated carbon, absorbing odors and discoloration, as well as through the dual-sided mesh of the Bio-Bag Filter, trapping debris and fish waste. The Tetra Whisper 10-30 Internal Filter adjusts easily to high or low water levels with a mounting clip. Each unit includes the filter, air pump, 2 feet of airline tubing and one Tetra Whisper Bio-Bag Filter cartridge.