I am building an above ground pond, I bought flagstone hoping to place it on the wall of the pond to make it look more natural. I am trying to find a good material to use to get the flagstone to stick to the wall, all the larger pieces will be flush with the ground so what I use doesn't need to support a large amount of weight. I have heard an idea on thin-set, stuff for laying granite and marble, but I wanted to get some more opinions. I am new to most of this stuff, but if someone could point me in the right direction, it would be greatly appreciated. thanks!