Determining floor/joist weight capacity

[sphelps]

Your 12" I-Beams, is that a steel beam I-beam or just a wood beam? If it's an I-beam do you know the designation? Same question for the "load bearing beam". For example W12x40.

I don't like the way it sits, I guess you can't have the tank sit centered over the two "I-joists"? As it stands you may get a titer-totter effect.

I'm not a structural engineer and I don't have the full picture but your floor support looks really strange to me, does that pass inspection these days?