I have an old house with a second floor with 3x3x14 rough cut redwood as the floor joists. I attached to them 4x4x14 redwood and put on top tongue and grove sturdy floor 3/4 inch. So combined, I have basically a 7x7x14 floor joist. My son wants to put a 90 gallon fish tank in his upstairs bedroom. It would lie on a single beam, maybe 2 (i cannot tell as floor is covered) running length wise on the beam. As water weighs 8.3 lbs per gallon, I estimate the load to be around 800 lbs US. Will that support the load?