Just set the new tank up 8 to 10 inches from a wall and you'll be fine. Don't forget to level it before you put in the water. Some floors are a little bit off and you don't want the tank leaning at all. It will weigh around 550 pounds, with water and all. The floor should easily support that much weight. The older buildings are just a sturdy, if not more so than the new ones.
"Fear not, my young apprentice. Just change the tank water."