One of my favorite tanks (and is no longer setup)
was the tank of Steve Weast of
http://oregonreef.com. He used very little sand in his display, and would vacuum a portion of the sand out with each
water change. When all the sand was gone, he would add one bag of sand back in the tank. One bag for a 800 gallon tank is not very much sand at all.
"To achieve the high water quality requirement, this system is set up along the thinking of a bare bottom philosophy…. namely, the removal, rather than the processing, of wastes. That means high flow, strong skimming, and a maintenance regiment that focuses on the removal of waste and
detritus. The only modification to the bare bottom philosophy is the addition of a small amount of sand. Since I subscribe to the bare bottom philosophy, but hate the look of a bare bottom display, I added a thin layer (around 1 – 2 inches) of sand to the
visible portions of the reef only. Yes, this means more maintenance (see maintenance section); but, the visual rewards are worth it." --Steve Weast