Currently preparing base for new pool. 33'x54" round (resin bottom rail). After reading multiple threads and internet searches, I am looking for advice on pool base. Ground is currently being leveled starting at lowest point and removing higher elevations. Hubby says sand 2-3", but after reviewing multiple install videos and threads/blogs, I am concerned about foot prints and our dreaded voles. Foam? I have read positive and negative. With the frame pools and bladders I wouldn't worry so much (and we have had several) but want to do it right. Many of the comments are that they can retain moisture and the pool liners sweat? Foam can cause gaps around frame and shifting? We have hard red clay under top soil how would that factor in? There was a great thread here about moisture content of various soils but a bit too complicated for me to fully absorb. Thanks! BTW my signature is for existing pool not new one.