There's a 4 x 39w Nova Extreme (the original version, not the Pro) on the 50g (36" x 18" x 20") here in my office. Sorry, as I don't have any pix, but we keep chalices, zoas / palys, and rics on the bottom just fine. I will say that the corals in the tank started looking and growing better once we switched out the stock bulbs for some UV and ATI brand bulbs.