I have a 55 gallon aquarium filled with nothing more than about 70lbs of live rock. I have been using this tank as a staging area to house livestock heading for the zoo display. There has been no livestock in it save a couple of snails and crabs for a few months now. I only add a ver tiny bit of mysis perhaps weekly to maintain the nitrobacter bacillum in the live rock. What is puzzling is that the skimmer on this tank pulls far more gunk out of this tank than the very same skimmer did on a 75 gallon fully stocked mixed reef tank. Also, I have a fair amount of hair algae taking hold in the 55 gallon tank. So my question is, what can be providing the nutrients to maintain such continuing skimmate production and algae formation? Skimmate production has not eased after about 3 months. One note, I never do water changes. At this point, the whole thing has become an experiment just to see what happens.