Glass cages tank will be heavier than your normal 75g built be All Glass or Oceanic, so that will only add to the weight. Problem being on the 2nd or 3rd floor is that if it leaks not only will you be paying for your apartment repairs but those under yours to. Insurance will help with this but im not sure if it will cover other peoples belongings...... Just make sure to Cross your T's and Dot your I's