You can try cleaning the site where the wheel rotates against the filter. I have read a lot of complaints about the filter's noisiness, but made a plastic 'T'-shaped barrier that hangs across the top of the tank, which lessens the turbulence on the surface of the water. This lowers noise and calms the water so the guppies don't tire from the current and duckweed can grow. The turbulence was such a problem because the filter is on the side of the tank, which makes it blow across the whole surface.