Egh, I just started this tank and i'm kinda... confused by it. I am trying to get something in there other than sand, so i started with some live rock. I heard this somewhere else... Would i be able to get some pieces of limestone and put that in there, then put the live rock and coral over it? I don't have enough money to afford all this stuff so if i could get a base and then build over it, that would be great. Also what are these powerflow (not sure about the name) or whatever. Something about water circulation... how important is that? Basically, i've just set up the sand, water, and 3 pieces of rock... does anyone have suggestions from here?