Eggcrate for rock

[Aquattro]

Originally Posted by jonn46

I have worried about pressure points or small areas of the rock putting all the weight in one small area on the glass.

Not something to worry about unless the rock is the size of a small car. Any rock you use will have either a fairly large single spot or multiple points of contact.
As an example of the strength of glass, I tried to remove a center brace once with a hammer. It was unbelievable how hard I had to smack it to get it to break. Unless you're throwing rocks into the tank, you have nothing to worry about