CJ,
Glad you started this thread. Do you know if vermeculite, sand and cement are better than sand and cement alone for the bottom? I know the vermeculite and cement can be indented, but it is suppose to provide drainage beneath the liner. My pool builder wants to make the decision on which bottom to use after the excavation. The price is the same for either bottom. I am wondering if I should insist on one or the other.