Im in the same boat with a 20g long with clownfish,firefish goby,dragon pipefish , purple urchin, sand star and 3 hermits. I also have a ton of corals. My tanks looking good so far been running for 3 months. I definitley moved way to fast and had some problems butworking through them also i fed way too much. I was feeding a mix of reef roids marine snow and mysis cube also fuel amino acids everyday.... Now im feeding every few days and my tank looks cleaner and corals look puffier. I also feed the fish pellets as needed but my pipfish lives off all my pods. I would feed very sparingly the corals your keeping wont need alot of food if any. Id say weekly coral feeding and watcher changes and pellets for your fish dailly or every other day.hope this helps. This is what my tabk looks like today.