Hey there, I am attempting to set up a 24' round AGP. The directions say to use "fine mortar or rock dust" to use as a base for the bottom rails and plates. I can't find either of those things in my area, so I was thinking of just using 3/4" gravel tamped down and leveled. I have the ground leveled, and made a ring of the gravel 2' wide and sand inside the circle. I am leveling the plates on the gravel, but am a little concerned because it seems really easy to move, and I'm not sure it's going to stay put once the pool starts to fill. Any advice would be appreciated, thanks!