Oh? Can't you just clean the bio wheels? Or get a new bio wheel? People say they are easily replaced and the box says you never ever have to replace themI have used a penquin once after a very old AC that was given to me used finally went down. After a few weeks I bought an AC30 instead, the so called "bio wheel" kept stop spinning which makes the whole purpose void. I have used AC for years on a 10g back when it was the mini and now have a 20, 30 and 70. Never had problems with the AC they last, easy to change media and clean. You can add water media layers you want in the amount you want.