My tank is pretty much set on live rock but eventually I will have to add more rock in the back to put more coral. I want to stack it real high. Was wonder is there anyway that I could glue pvc to the glass at the top and just rest one side of the rock on the pvc and the other side on the rock work that is there? I know it will probably not work because there is no way to get the glue to stay put for a period of time to dry. Should have thought about this before i set it up but did not think about it.