Just a quick reply on what the bacteria is doing. I don't believe it was adressed (unless I missed it).
The bacteria is doing about the most important job that is happening inside your aquarium. There is a scientific nitrogen cycle that the bacteria are accomplishing, but to put it simply, it is neutralizing the fish's waste and turning it into a much less toxic product.
By rinsing the biowheel under ordinary tap water, you will either destroy or severely damage the bacteria, thus restarting this nitrogen cycle all over again. Any fish you have in the tank will be negatively affected by doing this, especially if you are stocked to the limit or overstocked. Basically, destroying this bacteria will cause the fish to be swimming in their own waste and it will build up to dangerous levels.
Like has been mentioned a few times, when you do a water change, dip the biowheel in this water to clean it up a bit. Also, just make sure that your filter media is clean like has been mentioned just to make sure this isn't the issue. Rinse your filter pad(s) the same way, by dipping it in old tank water taken from the aquarium. Every time my biowheels have slowed down, cleaning or changing the filter media has them spinning normally again. If this isn't the problem, maybe something is causing the wheel to stick. See if you can clean around where the plastic and metal connects on the side of the wheel, but don't touch, rub, or scrub the actual bacteria medium or again, you will disrupt them and may cause the tank to have to recycle and this will stress your fish.
Just wanted to make sure that you understood exactly what the bacteria is doing and how damaging it in any way might affect your fish. Also, just so you know, the instructions for the biowheel say that a biowheel spinning at ANY speed is doing its job. Even if it's moving slow, it is still doing its job of neutralizing fish waste. The only real reason for concern is if it stops spinning completely.
Paul