I have 2 marineland penguin 100b(rated 20gal) on my 29 gal. The bio wheel on one won't turn and the media on it is drying out. I've tried replacing the carbon cartridge, thinking it may be to clogged to allow waterto flow through. I've lifting that upto allow water to go under it, or pushing it downmore. Nothing works. The filter has the carbon cartridge, 2 pot scrubbers and thhe bio wheel. I clean it once a month or so, taking it all apart, rinsing(keeping filter media in old tank water and rinsing filter parts under tap). What could or should I do? Thanks!