Before getting this filter, I was struggling to keep my 3 gallon tank water clean. It was cloudy, had debris, and the undergravel filter and aeration system with regular water changes just wasn't cutting it. I know there are smaller filters for three gallon tanks, but I felt getting something for a bigger tank might help keep things clean. And BOY was I RIGHT!
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Great for turtles by KenD from Springfield, MA08/22/2011
Prior to finding the 40i Whisper in-tank filter I was using Fluval U3 and U4 underwater filters in my Red Eared Slider tanks. They were OK but very messy and expensive on filter cartridges, which didn't last very long. I find the Whisper filter cartridges do a better job, last longer and are less expensive to replace when bought in unassembled 12-packs plus are so much easier to change. I am very happy with them and they are ideal for tanks that are only half filled, as with turtles.