In my 60 gallon system, (40B and 20sump) I change about 1 gallon everyday. Yes honestly.
Any my skimmer still pulls out the nastiest stuff you can imagine. I wonder what those anemones are doing all night. LOL
I saw one very similar at SWF today when I was there, getting a fish net and a few other things.
They even had a really nice Escenius sp. Blenny that I haven't ID'ed yet. Shoulda bought it.