rock wall, glue it or egg crate?

[BMW Rider]

Originally Posted by Fishward

I built a wall out of eggcrate and cement. Worked out great. You need architectural cement, you can see the results inmy photo gallery
def suggest going with the eggcrate however you choose to fixthe rock to it.

I did the same for my tank. I just used regualr cement and mixed up a batch of aragacrete (cement, aragonite sand, crushed coral). After a good long cure, it went in the tank and was soon covered with growth making it look totally natural.