I live on the upper level of a duplex; the neighbors have the basement unit below me. I have a 30 gallon set up in the living room right now, and recently got a 75 gallon to upgrade. The thought hit me tonight, the tank and stand is pretty heavy by itself. Once gravel, water, and decorations are added, it is going to be very, very heavy. How big of a tank would you trust setting up on a second story? It's not a terribly old house (built in the 90s), but the last thing I need is for the floor to give out and the whole living room to go crashing down into the neighbors living room.