Floor support, 1 or 2 jack post?

Hey all, I am hoping to get some helpful opinions. My 75 Gallon w/20 Gallon sump and goodies is going on the first floor of a townhouse. Below is an unfinished basement. The tank is situated on a non load bearing wall. My plan is to put a 4x4 perpendicular to the joists spanning 3 joists with a jack post centered on the middle joist and the 4x4. The jack post supports 9400 lbs at full extension.

I got to thinking and thought maybe I should use 2 jack posts, one on each end vs 1 centered. Would 2 be overkill since they would only be about 2-3 feet apart? One not enough? Any opinions?

Here is a drawing

 

Are the joists running parallel to the DT, or perpendicular?
If parallel, then it's good security to brace as you say.
If the latter, might not need anything?
How far away from a load bearing wall is it?

 

They run parallel to the DT like in the picture. The tank is dead center of the room and the load bearing walls are on each side maybe 10 feet away on each side.