I recently got an undergravel filtration system to go in my 30 gallon tank to help my Penguin 125 cope with the load. I also got a powerhead for one side of the filter, but I got to thinking: What does a powerhead actually help? All it does is make water go through the gravel faster, not actually filtering anything. So this is what I did... I went out and got some carbon and put about 2 inches of it down the tube that my powerhead was sitting on. Then I put the powerhead guard on top of the tube and stuck the powerhead on it. Turned it on, and blamo. It works. My thought process tells me that it was a good idea and it will help with the filtration. Anyone else have any thoughts about the idea?