I just had my old hot tub removed, and am having a new one delivered. One problem is that the pavers that were the foundation for the previous hot tub (which was here when I bought the house ten years ago) have sagged about a half inch in the middle. One person suggested just pouring some quickcrete over the pavers (I am planning on using the patio mud version) to level the area. I think this should work because the previous hot tub probably packed the ground underneath the pavers, but the layer of quickcrete would be pretty thin (1/2 inch, but that's ok according to the instructions on the quickcrete bag).
Has anyone in this forum ever tried this? It seems like a fairly unique situation.