HOT magnum filter media, etc.

I'm reclaiming a long neglected 20 gallon tank that is overrun with algae
and "christmas moss." It also has java ferns, and a few sword plants, and
another stem plant whose name I can't remember right now. Hygro
polysperma, I think.

I did a 50% water change, and vacuumed a bunch of nasty crud out of the
tank. I put some goldfish in to root around and keep things stirred up
(also I like goldfish). The tank is looking a lot better already, and I
haven't started pruning the plants yet.

I just bought a HOT Magnum filter and am playing with it now. I stirring
the water really good and everything was green and cloudy. I put the
standard filter in (with no charcoal) and it didn't seem to do anything. I
put the micron filter in and it's doing an OK job but it's about clogged up
already after only 20 minutes.

Can I use polyester batting in the chamber of the regular filter? Or is
there some other way to use batting or sponge for a high capacity filter?
Or should I just use the micron filter and clean it twice a day until
things are under control?

Thanks, and best regards,
Bob