You could try feeding some vegetables. I had the smae problem, but if you steam some corgette (put it in a tiny bit of water on a plate and microwave it for 10-20 seconds) then put that in the tank (you cna weight it down with a plant weight or you can buy special screw thingys)
Leave it in overnight and hopefully the plec will eat it after the lights go out. If you don't have corgette you could try some cucumber.
I keep my q tanks filter media in one of my other tanks filters, when needed, i set up the Q tank, fill it with water (half new and half from another tank, make sure it's the same temp, then move the media over.
I've never had any problems, and some people do it differently.