Determining floor/joist weight capacity

[dabandit]

I am a contractor and i would stronglly advise against it,the issue isnt how much weight the floor joist can bear its how the floor joist is attached. Most floor joists are attached with a saddle bracket which for a period would support the weight,but your problem is a CONSTANT load of over 1400lbs which they cannot support, in time with vibration the nails will pull out. Ok..that said,now you need to determine whether the floor sits on a lower wall or if it sits on brackets....you follow? p.s the wieght rating of an i-beam is over 1000lbs not 600 as mentioned so there is no issue there. Is your basement finished? you could frame up a supporting wall very cheap or buy a steel shoring post anyway I hope that helps. I'm around here alot if you need more info or clarifying. Good Luck sounds like the tank will be worth it