D-I-Y replacement filters for penguin bio-wheels

I have two penguin filters for my tank: a penguin 330 and a penguin mini
(had it from my first 5g tank, figured I keep using it). Replacement
filters are expensive, so I thought I would find or make cheap, but
effective alternatives. The 330 has media baskets so I could stuff them
with filter floss or something else, but I wouldn't be able to do this with
the mini. I want to reuse the original penguin filters somehow.

My ideas a
1) Scrub clean the filter pad between. Although, I haven't had too much
getting off all the old gook though...
2) Separate the top of the filter from the filter pad and remove and replace
the carbon through this opening. Use a clamp to keep the opening shut.

Any input appreciated,
E.Otter