I have a Aqua Clear filter rated for 10 gal
max together with a Penguin Bio-Wheel filter.
The wheel will move by itself with the water flow, since the wheel sits on top of the water fall channel. The grinding sound is perhaps some loose carbon media that got stuck in the impeller housing, or just air trap in there. I usually pull or lift the snorkel or pick-up tube and allow the water to enter the pump impeller...
Check first your manual, it should have the instruction on how to take apart the filter for cleaning, if not, simply empty the power filter housing of the water you put in, take of couse the filtering media, then lift the pick up tube from the bend. It should come up about 4 or so inches before its free from the housing. From where you took out the pick up tube, that round hole is also a separate part that can be take out, just lift it up and ill will come out pulling with it the impeller little magnet and blades... look into the bottom of the filter housing from where the little magnet sat and check with a flash light if there is any particles of carbon or anything else.. if any..clean it... check the blades too for any damage . then just put everything back starting from the last piece you pulled.
Good luck, good filter, hope this helps you out.