I have a 150 gallon FOWLR tank with a 55 gallon sump. LOTS of live rock. I run a protein skimmer in the sump. My tank is doing great. My protein skimmer is working great. Only issue is that it stinks. Like stinks up the house stink. I know it's working, it has lots of dark skim, but it stinks. Does anyone run a tank without any filtration other than live rock and water changes?