I read some things online but nothing about my particular filter. Here's my take on using a sponge and PLEASE correct me if I'm wrong.
I have a Top Fin 10 that came with the tank. There are two slots, one holds a plastic base with a thin pad attached that slides into the slot, in the other slot the carbon sack slides in. From what I gather I take out the carbon sack and cut a piece of aquarium sponge the same size and push it down into the slot. When I do water changes I rinse both pieces in the bucket of water that I removed from the tank. Does this sound right?