90g display and 30g sump. don't have one yet but am not against the idea. 2 ocellaris clowns, a coral beauty, a lyretail anthias, and a cleaner shrimp. I did have a sleeper blue dot but havent seen him in a couple of weeks. Is it a bad idea not to have one? Im new to the hobby and dont see the reason to if water changes are done regularly. Someone here will correct me if im wrong.