How large of a tank would you...?

One question, is the place built out of Wood or Concrete? Allot of Apartment building floors are built out of Cast concrete and walls are Cinder block. Some places that appear to be built out of wood even have Cast concrete floors. If its built out of concrete then you could put as big a tank as you want. Wood, well I would not go much bigger than a 75.

 

That's a good question and one I researched a bit when I was deciding what to put in my current 2nd floor house/apt. If you have access to the basement check and see how the joists run on the 1st floor, they should mirror the 2nd floor. If they run perpendicular to the tank than you should be ok for say 75g and under, but every house is different. Def would put it against a load bearing wall too. My current home is a very old house, some say they were built much sturdier than newer houses.

The dilemma of weight on a 2nd floor is that it's the bowing and flexing of the floor that will be the worry, causing the tank to split seams, etc. It's that 24/7 pressure that is hard to measure, not like some say "you can stand in a bathtub and the floor won't collapse" analogy.