Quiet, economical filtration performance of the classic Whisper 40 Power Filter is great for freshwater or saltwater aquariums. Energy-efficient designs feature low-wattage motors and adjustable flow control. Bio-Foam cultivates and maintains a bacterial bed for biological filtration, while easy to replace Bio-bag cartridges take care of chemical and mechanical filtration. Bio-Bags included. Measures: 8 in. x 4.5 in. x 7.5 in. The Whisper 40 is rated for aquariums up to 40 gallons, and has a maximum flow rate of 210 gph.
For more information about the Tetra Whisper 40 Power Filter, see the Manufacturer's Instruction manual.
I used Whisper power filters for many years and was able to adjust carbon and use ammo chips if I chose. Once I got the hang of it, I never had a problem. Recently started my aquarium up again and could not by Whisper locally. I have tried 3 different major brands and each was its own type of disaster.
You must be doing something wrong.
Make sure the impeller is seated properly in the motor, and keep the level of water in tank to top.