Another rock in the center of the pool has come to the surface yet another sharp one. We can't take the pool down again, we just put it up lastnight for the second time. I was able to loosen the rock abit, I patched it but I'm not sure if the patch is stying, we have a bag full of rocks for the vollyball game I put that on top I'll leave that for a few hours until my eldest comes home to check again. I'm hoping this works.