If you have sufficient live rock (LR) you should have plenty of beneficial bacteria an don't need the biowheel to serve as your beneficial bacteria house but instead as mechanical filtration in which case replace it.
you are never supposed to clean your bio wheel from what i've heard because bacteria builds up on those wheels overtime ...my bio wheel was white and now its slowly turning to a darker color just leave it alone but one thing is that if you clean your power filter make sure the bio wheels are wet by just placing them to float on top of your DT because if they get dry it's not a good thing...o and also you will notice the wheel spinning slower as well overtime from the bacterial buildup so its a good thing
Originally Posted by NEreef http:///forum/post/2534670
take some water that you have syphoned out of the tank. then swish and scrub the biowheel in that water, if you wish to clean it.
+1 on that. I had one get particularly nasty after 5 years or so. I flushed the chunks out with tank water and stuck her right back in. Otherwise I wouldn't mess with it. Turning a nasty color is normal.