Review on Tetra Whisper Power Filter 10 Gallons: Silent 3-Stage Aquarium Filtration for Optimum Cleanliness (26316) by Brian Wright

I purchased this Whisper PF10 external filter to replace the internal one in my 10 gallon aquarium because the old one was taking up too much space and not disturbing the water surface enough. resulting in the fish having a harder time breathing the air. With this new filter there is now plenty of oxygen; the fish no longer fight for air. Also, they have more space to chase each other. The bad thing I found was that the inside was a lot quieter than the outside. This prompted me to get back on the internet to see if I could buy a quieter external one. However, before taking that step, I decided to see if I could make my PF10 quieter. As it turns out, this is easy to do. The filter has a black semicircular disc that rests on the back of the tank to stabilize it. Unfortunately, the drive vibrates and hums loudly. I'm sure it must annoy the fish. Placing a piece of sponge between the disc and the tank eliminates the noise, making the PF10 a real sentinel. Update: after almost a year of use I have to say this is a loud little filter so I'll have to look around for something new soon.