basically 270 gallons of water volume whew, I dunno man, I'd probably think twice about it. Rock weighs more than the water that it displaces. I'd say keep it downstairs. I had a 125 reef and lived on the second floor of an apartment building and I worried quite a bit, I can't imagine doubling that. I know it's possible and people have done it, but if I were going to do that, I'd try to get the floor braced to accomodate for so much weight in such a concentrated area.