If you did filter maintenance, did you clean the intake tube and impeller assembly? If the impeller is plugged with gunk and/or the intake tube partially blocked the water could be flowing but not at the correct rate and not enough force to keep the bio-wheel turning. Try to manually turn the bio-wheel and see if it turns freely. It could have just gotten dislodged a bit from the track it sits in. You will also want to check the position of the filter pads, if they did not quite get set down into the area completely or are a little out of line they can be causing a problem. If you check all these things and nothing helps, then you need to take the filter off and take it apart and go into the impeller assembly and see if there is something stuck in there.
I hope this helps, bio-wheels are some of the finest filters that are made so it is really more than likely some very small reason why this is happening. As long as it is not totally stopped and not moving at all, you are getting some filtering. The biological bacteria needed to control the
ammonia live on the bio-wheel so it is important to keep it wet with aquarium water to keep them alive but they do not all die off immediately. Just try to remain calm and not shook up and it will be easier to work on the filter. I will be on for a while yet and keep watching for this post so I can get back to you if need be.
Just a quick note, you do not have to change the filter media as the manufacturer recommends. They sell a lot of filter cartridges that way. When you change the tank water, just rinse the pad out in the USED tank water and put it back. The bacteria that live on the pad will not be lost that way and you can keep using the same pad unless you need to use medication in the tank and then you need to remove the carbon filter and put in a non=carbon based filter media or remove the carbon from the filter cartridge. The pad can sometimes be used for a year or more.
Rose
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