You'll have over 1400 pounds of water and depending on if it's glass or acryllic and all the equipment another several hundred pounds. Don't forget to factor in a fuge if you plan on one.
The flooring depends on many factors such as floor joist spacing, whether it's pier and beam or studwall construction. It also matters greatly where you plan on putting it, say the middle of a room versus near an outside wall where the joists are tied into the support footings. With something that big I'd want a minimum of 2 x 8" joists. Supporting it underneath shouldn't be to hard.
Down here most homes are built on concrete slabs so it's not an issue. HTH