I can't find this answer anywhere in the forum. I've got a 18x33 Vogue pool I'm sinking about 27 inches in the ground. If I have all the post on paver's leveled within a 1/2 inch, does the interior ground need to be level? I've good, hard caliche dirt (clay dirt) for a base that has a little "wave" to it. The wave isn't more than an inch at any one spot. I'm going to place 1/2 foam for a base then the liner. Am I good or should I bring in a load of sand to level those low spots through the middle.