I spoke to a pool company and they said that when installing an above ground pool you should "dish" the ground in the middle. This meaning that you make the ground in the middle of the pool 3 to 12 inches deeper than the rest of the ground. Everyone else that I have spoken to has said to level the ground completely. This company has been in business for 35 years. Has anyone heard of "dishing" the ground in the middle? Thanks!!