Tetra Whisper 4 Gallon Internal Submersible Water FilterThe submersible filter includes a 3 stage filtration system with a dual sided Bio Bag mesh, which catches debris and fish waste while the activated carbon absorbs odors and discoloration. The bio scrubber features an anti clog design for convenient and easy maintenance. The bio scrubber also has a solid back, which pushes the water making it flow evenly over the bacteria rich bristles for supreme performance. This filter is compatible with Tetra Bio