Tetra Whisper Power Filter for AquariumsTetra Whisper Power Filters are the best selling brand of power filters in the U. S. Appropriate for every size aquarium, they provide the three types of filtration that your aquarium needs: Mechanical Filtration Removes uneaten food, bits of plants and fish waste Biological Filtration Provides for growth of a colony of beneficial bacteria that will eliminate harmful toxins in the water Chemical Filtration Activated carbon removes compounds that cause