I am install a 33 ft fiberglass pool and plan on building a grotto with natural boulders. I will be cutting the stone to fit over the pools edge to give it a natural look as oppose to placing coping in the areas along the pool where the rock will be. I plan on cutting the stone to fit over the top of the pool so that the rock isn't resting on the fiberglass as this is obviously a lot of weight that would be sitting on fiberglass pool edge and possibly damaging it. My question is, would it be better to first pour the concrete beam around the pool level with the top of the fiberglass and then place the boulders on the concrete or would it be better to place the boulders on well compacted gravel and then concrete them in around the pool? Any info from someone who has done a similar project would be greatly appreciated.