We are planning on purchasing a 21 x 41 oval above ground pool and sinking it about halfway. I went to a doughboy dealer. The pool he recommended was nice with a vsp Hayward 900 swim clear. The liner options are minimal. Can I get a replacement liner from someone else? I found a 30 ml beaded liner online. The salesman was putting down other liners, saying doughboy liners are superior. Is this true? Can I use another liner? or who can I order a pool from?