I'm in the process of setting up a glass 80 gal aquarium. As all of you know glass aquariums are unsupported on the bottom(edges only), unlike plexiglass tanks. I'm planning on having a lot of rock structure and am somewhat concerned that I'll overload the bottom glass. Obviously the rock displaces water but the density of rock is huge compared to water. I've seen all the latest Marine setups which have alot of rock so my guess is that the tanks are designed for much more load than water and gravel. Does anyone out there have any info on safe loading?