Tetra® aquarium products are dedicated to helping seasoned hobbyists and beginners alike enjoy a successful, life-long aquatic experience. Tetra products build fish-, reptile- and pond-keeping confidence, one innovation at a time. Our complete line of Tetra® nutrition, water care, filtration and aquarium products help make fishkeeping accessible to all hobbyists so they can benefit from its rewards. The Tetra® Whisper® 4i Internal Power Filter for 1-4 gallon aquariums uses small cartridges to provide three-stage mechanical, chemical and biological filtration. Water flows through the cartridge floss, trapping debris and fish waste, while Ultra-activated® carbon removes odor and discoloration. The 27 GPH motor 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 allows aquariums to be positioned as close as 1 inch from the wall. The adjustable, universal clip and suction cup allows for a variety of setups to easily adjust to high or low water levels. And, the cord organizer keeps everything neat and tidy. FOR 1-4 GALLON AQUARIUMS: Tetra® Whisper® 4i Internal Power Filter uses Small Whisper BioBag filter cartridges that are easy to change. 27 GPH MOTOR: The internal 27 GPH pump cycles a 4 gallon aquarium more than 6 times per hour. POWERFUL FILTRATION: Water flows through the cartridge floss, trapping debris and fish waste, while Ultra-activated® carbon helps remove odor and discoloration. SPACE-SAVING DESIGN: Your aquarium can be 1” from the wall with the internal filter designed to clip on your tank wall and be hidden by décor. ADJUSTABLE: Adjustable clip and suction cup allows for a variety of setups to easily adjust to high or low water levels.