I have 2 tanks one with a skimmer and one without. My 75 gallon is crammed with corals and I have a 45 gallon refugium with lots of live rockand plants and a seperate 25 gallon sump which filters beautifully. I swear my 125 gallon with refugium and skimmer is never as stable as my 75 gallon without. I think the key is lots of liverock and a good refugium. Corals need good lights more than a skimmer IMO, However if you dont have room for a good size refugium than definately get a skimmer. Carrie