how much is the difference lighter then say a 240 size....glass>acryllic.. i assume the glass would be super heavy. and i'm wondering if the 240 acryllic how heavy is it? (tank only, empty)
4-10 times seems way too high. 2-3 times would be more accurate.
Acrylic is .0426 lb/cu. in, glass is .0889 lb/cu, in. Glass weighs roughly double what acrylic does.
Unless the glass tank was made from twice as thick of material (not typical) it isn't going to weigh 4x what the acrylic tank does. To weigh 10x what an acrylic tank does the glass tank would need to be 5x thicker than the acrylic (not a chance).