Recommendation For Hospital Tank

It can be advantageous to have different types of media for various reasons including trapping debris of different sizes so, if you could keep the sponge but put ceramic media in place of the carbon, then that would be a good plan. I'm assuming that the amount of ceramic media you'd be moving across from the main tank's filter is about the same fraction of media from that filter as the being-quarantined fish is to the total number of fish ie if you have 20 fish, then you're moving across 1/20 of the media (or body mass of the being-quarantined fish relative to body mass of the total number of fish as I'm aware you have Bertie/the large-ish BN plec)?