Great for turtles
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.