MTiller, just so you know, it was a good thing when the wheel became that color. It meant nitrifying bacteria was building up which took the ammonia out of your water. If you read documentation that came with the filter, it says you should never replace the wheel and wash it only when there is clear algae or other debris built up or if the axels get gunked up and the wheel stops spinning. Hope you didn't switch to another filter because every time you cleaned the wheel, the tank got nasty.