Today I purchased a 250 acrylic. It was cheap, $1350 for the tank, 3 400w MH lights, 70 gal sump, new RO unit, stand and canopy, some live stock, and about 50 lbs of live rock, plumbing and an oversized return pump. I could not pass it up. Not a big fan of 30 inch tall tanks, but it will do, just could not pass it up. Poor guy lost electricity, and most of the things just did not make it. Frustrated, he sold it. I want to take down my 125 and set the new one up, problem is, I really need or rather want to use the same spot as the 125 is sitting in. Is it possible to do a switch within 48 hrs or so, or the danger is too great to my life stock? I have no idea how to do it, and not sure if there are any major draw backs, or if there are any advantages. Perhaps someone has done that before. I already have about 125-150 lbs of live rock in my tank. His tank has lots of sand, but its kind of dirty, don't really want to use it. If I do the switch, is there a possibilty of a cycle, or will my live rock keep the tank stable? Should I use my water, or add all new water? I really do not have idea, please help before I do something stupid.