I have built a square sandbox from 16' 4x4's for an aboveground pool. Our 14' pool finally gave out, and I'd like to install a 16' round Ultra frame, but I'm not sure it will fit. The inside dimensions are 15' 9". I've searched here and saw where someone said their 15' measured 14' 8" at the ground. If the 16' is similarly sized, I think it would work. Does anyone have one that would be willing to take a measurement at the widest point at the ground for me, including the vertical supports? Many thanks!