I own a skimmer, its in my sump, but not plugged in. I have about 60 -70 #'s of live rock in my tank and my tank is doing fine minus the fact my a/c went out a couple times. I keep zoanthids and mushrooms.. My new tank is only a few months old, but from my experience in my last tanks zoanthids grew like crazy and were very colorful and i didnt use a skimmer.