How heavy are these things?

[Scuba Diver Gal]

In the process of making a deal on a Red Sea Max 250 for my son's bedroom when I thought "holy cow, how heavy are these things?". This tank will be in my son's room on the second floor of our house (above our garage). It will be on an outside wall but it is not a load bearing wall. I am guessing the tank will be almost 900 pounds. Do you all have your tanks on concrete floors?

Sorry if this is a dumb question but my husband really doesn't want this tank, especially if he comes home and it's fallen into our garage!!!