This is just a rough diagram of what I would like to build. i would like to have a 55g main tank with a 20g refugium, both set on one custom stand. i like the design of having the refugium above the tank so that gravity will cause the water to return to the main tank. I was thinking the 55g would be a reef, and the 20g could make a refugium with a longspine urchin and a couple of Urchin Clingfish. Just a thought, any input?