Yesterday I cleaned my fish tank. I took the filter out so I could take the tank to my sink. Besides that, I did not touch my filter at all. When I was done cleaning the tank, I put the filter back in, but it didn't work. The air pump was vibrating a lot (in a very loud and obnoxious way), but there was no air going through the filter. Does anyone know how to fix a problem like this? There isn't any gravel in the filter, so I don't think there's any kind of blockage. I really don't want to have to go buy a new filter (I don't have the funds to do so anyway) so if I can fix it, that would be great. Thanks!