Best way to build swimming pool bottom ask experts of long island

Client in Indianapolis
We have talked to several pool companies in Indianapolis and are getting difference answers. In Indiana, what is the best for bottom for an in ground liner pool. How do 6bag mix concrete, vermiculite, and mortar compare. The pool will be built at the top of a sloped hill that ends up in a retainer pond so we should not have a problem with ground water. Each build tells us that their way is best. Now we are confused. Can you help answer our question?
From Giuseppe Abbrancati
Every one has a way of doing it and one is not better then the other because in the end they all achieve the same thing and that is making the bottom of the pool hard this way you don’t get foot prints, and anything that gets hard is good. The way we do it is by mixing sand and cement in a dry mix, and the reason we do it this way is because we can make the pool bottom very smooth and you will not see any imperfections in the liners when the pool lights are on at night. Also in the future if you need to replace the liner there will be nothing you need to do to the pool bottom.