depends on beams. 75 gallons of water X 5lbs. per gallon =375lbs +rock+sand+actual tank, stand, canopy,+the weight of two people standing in front of it. I know that can be done in a mobile home and you know how cheap they are made. I would find out which direction the beams run and run my tank perpendicular to them spread over 2 or 3 beams to try to distribute w8 evenly. I wouldn't do it if the beams are less than 2x6, But I would feel safer with 2x8 beams which is becoming standard in most newer homes. Also its rare but make sure the floor isn't made of partical board. If so you might find your tank back on the first floor one day. Also if you put it on the second floor over a substantial wall on the first floor, that would be more added support.