How much weight can tanks handle?

Putting plywood base on the stand and a sheet of foam and the tank on that is the best way to support the tank and putting egg crate/light biffuser on the bottom of the tank and do as jessicar613 sugested and all should be fine.
 
I have a LOT of rock in my 75 gallon convict tank. The light diffuser method works great. It keeps the rock off the glass bottom and also stops the convicts from undermining the piles and having them fall into the sides of the tank.
 
AquariaCentral.com