Determining floor/joist weight capacity

[sphelps]

Originally Posted by newreefer_59

It is about a foot from a load bearing beam and about 40% of it is riding over 3 perpendicular joists. Those two facts I like. Where my concern lies is the other 60% of the aquarium is over a single parallel joist that attaches to the perpendicular one. Kinda hard to describe. Can I scan a drawing and display it here?

Oh, and the tank is 2'x5' with sump already plumbed in under the tank.

That's starting to sound a little risky and I can't give a professional opinion and you won't likely get one here. There's no doubt the floor will hold but what happens when you have a party and all your guests crowd around the one side?

The tank weight should be evenly distributed, lengthwise across a load bearing structure and perpendicular to floor joists. Other scenarios are harder to analyze and you'll likely need to send drawings in or have it professionally evaluated to get a correct answer.