I had 135g + 25 sump on the third floor and it worked fine for over two years. It is six feet long and was against a load bearing wall. (the same wall ran all the way from 4th floor through basement.) Everything was great till move day, once we moved the tank we could see clearly that the floor was 1/4 inch lower along the wall where the tank was! We lost our $500 deposit but nothing was ever said about further repairs.