We have a 5 gallon with live rock and live sand and some green star polyps, snails, 1 hermit crab, and a brown cheeked blenny which stays very small. We've had it for about 6 or 7 months, no protein skimmer just a filter minus the carbon and a small powerhead, haven't had any trouble with this tank at all and it has so much life in it. Good luck with your nano!