I finally get to see the project that we have been talking about in chat.
Looks good so far. I think it would like so much better if you could get some more rocks and stack that higher, but I read that they kept toppling over, so that might be a problem. If it is a huge problem, you could by some slate and start stacking that, you can make so many caves and such with slate, I have some in my cichlid tank and it works pretty well.