We have a Wilbar Quest 27' round pool that has been in storage for the past 6 years. We want to install it in our new backyard, but would like to make it smaller. We are thinking 18' or 21'.  I know we need a new bottom rail kit, but I didn't see a kit listed, only the individual rails for the 27' quest. How many individual rails do I need to purchase to make the pool 21'? We bought our pool around 2006/2007.