To use mortar you have to be quick and know where your going or mistake can happen i found that out last night. They say you have 15-20 minutes to of work with the cement but sometimes the material bond much more quickly so be aware of that. So have a plan and a back up plan. you'll see what i mean. To view the finished tank with corals and the build up thread go here; http://www.thereeftank.com/forums/f6/two-cats-and-two-tanks-build-up-meow-210457-2.html i used marco's rock cement at firs now i use this one very easy to use and good. AQUAFOREST STONE FIX 1.5KG http://www.incredibleaquarium.com/index.php?main_page=product_info&cPath=21_127&products_id=5603 its available in Canada and the States. http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=33324 Another one i didn't try yet is NYOS Reef Cement https://www.youtube.com/watch?v=yIZdzUfQgpI amazone https://www.amazon.com/NYOS-Reef-Cement-500-ML/dp/B00C1T3BQ8