CA is Cyanoacrylate or standard superglue. I used Bob Smith glue in various viscosities. I glued the rocks together and used a spray bottle with water / baking soda to instantly set the glue. (DO NOT buy accelerator, its a huge waste of money and smells awful) Then I took a thicker glue and filled the gaps and sprinkled sand over it. Within minutes its cured and looks more natural than the grey mortar. Tidal gardens and BRS did videos on it, but BRS did a more mortar approach. I wasted a bunch of rock with the mortar. It always ended up bulkier than what I wanted. I did use a spray bottle when using the mortar to "blend" it into the rock. I really just used the mortar as structure underneath the rock on arches and the base where you can't see it. I would suggest getting different thicknesses of the CA glue. I found uses for the watery thin stuff all the way to the thick gel. The medium works best to mock up your structure. I've been fiddling with my scape since April while setting up my Red Sea P650 and have tried everything. If I had more rock I'd probably start from scratch, but I'm not paying for another 100 lbs :mad:
DO NOT use the baking soda spray or accelerator on top of the sand or it will turn white and stringy, let that cure on its own, that will only take seconds to a few minutes.