It might be bad because it will make it impossible to clean the panes of glass that any rock is leaning against. This may or may not be a problem... the only other one I can thing of is that having rock stacked like that can lead to dead spaces with little or no water movement, which is bad.
I would use an epoxy to stick the rock together, or drill the rocks and use PVC or acrylic rods to build your structure, so it is stable.
__________________
Calvin
---
Planning a 29 gallon mixed reef...
|