Just run the two various foams in the bottum. Then the ceramic rings topped off with the white floss and you should be fine.
Seing how you have an Oscar with various Cichlids, you'll want to make sure you do weekly (maybe even every 4 or 5 days) WC
's religously to keep the water para's in check. Seeing how your tank mates are sloppy eater's you'll want to stay on top of Amon levels, as well as, do monthly filter cleanings (use spent tank water to rinse the filter media, don't rince the ceramic rings, so that you don't disturb the bacteria colony to much).
Are you sure that 55g is'nt over stocked? Those fish have the potential to get rather large. Factor in they are heavy/sloppy feeders and you might have problems in the future.
I can't stress enough how important it is to get a basic understanding of water chemistry to get the full potential out of your canister and keep a healthy, thriving tank.