From its claim to fame as the “World’s Most Popular Fish Food” to the consumer-friendly TetraCare support, you can always trust your tank to Tetra products. Since 1995, the company’s goal has been to make aquatic pet ownership easier, and we continue that tradition with our complete lines of nutrition, water care, filtration and aquarium products for fish, reptiles and amphibians.The Tetra Whisper Internal Power Filter for 4 gallon aquariums uses small cartridges to provide two filters in one (mechanical and chemical). Cartridge floss catches debris and fish waste, while Ultra-activated carbon removes odor and discoloration. The 27 GPH pump cycles a 4-gallon aquarium more than 6 times per hour. Easily change cartridges with the hinged lid for easy access. The space-saving design is easily hidden by décor and can be adjusted to high or low water levels with the adjustable clip.