Well I decided to try something new today, instead of replacing my filter cartridge in my penguin-bio-wheel with a new one I decided to throw in some filter fiber I had laying around and see how it worked. Well I put in enough to make the wheel spin and so far it's doing great. All that is different then the regular cartridges is there is no carbon. Before you decide to do this let me finish expierementing to make sure it's works good but if you want to do it to you can. It's a lot cheaper for me ;D and is a lot easier. Let me know if you do this, see any flaws, or are going to try it.