A 75 gallon aquarium is a great addition to any home, but you need to make sure your floor can support the weight. The average 75 gallon tank weighs around 850 pounds when full. That weight is distributed over the entire bottom of the tank, so it's important to have a strong foundation. Most homes have floors that can support this weight, but if you're not sure, it's always best to check with a professional before setting up your new aquarium.