It's a single stand with grow bed on top, two tanks in the middle and one (sump) below, effectively laying on two 8 feet 1x4 boards flat-side to the floor. So fairy well distributed.
Thanks, I didn't think stud finder would work on floor joists, have to try it when I get my hands on one... Didn't want to place it all on one joist in the middle and have bunch of friends stand around at the same time...
If I recall correctly, minimum capacity is something like 40lb per square feet, so technically the room is good for 2-3k lb total, but who knows how heavy friends can be...