Oh yeah, i forgot. The appropriate amount of live rock is whatever you want. If you're also running a good sand bed, you don't really need the rock for biofiltration. If you're running no sand bed, just make sure there's enough rock to make it look the way you want. You don;t need to fill the tank as so many people do. In fact, it's much easier to get a nice flow characteristic in the tank with less rock.