I guess my concern is hearing from folks down florida way that say they can't drain at all because of their water table is basically just below the surface of the ground. You maybe already know this, but think of your pool like a concrete boat (they had these competitions in schools sometimes). Concrete boats are heavy, but if they are lighter then then amount of water they are displacing, they will still float even if they have some water in them. In the case of a pool even lowering the water level a couple of feet could "lighten" it enough to make the remaining water and concrete lighter then the weight of the volume of water the outside of the pool shell displaces.