No cement. They sit, and are locked, pretty tight. As I'm sure most everyone here knows: It took 3 hours one day, 2 hours the next, and 2 more hours after that to get it how I wanted it.
As far as the substrate goes: I read a few books, read a lot of posts on the forum, and asked a lot of questions at my
lfs. But I am just a rookie in this avenue of the hobby. I'm told it is not
cc. It is aragonite based Fiji live sand. One third live, two thirds dry.
Thanks for the comments. All comments are welcome as that is the best way to learn.
Rick