Greg Miller wrote:
I started building a stand for my new 120 gallon tank,
but have gotten cold feet after calculating that the
weight of the water will be roughly 1.4 metric tons
(12 pounds/gallon?).

1 L (water) = 1 kg
120 gal = 454 L = 454 kg


tank dimensions are 24"x24"x49.5"

That tank size contains a max volume of 467 L. It could therefore weigh 467 kg