My sand filter came with an explanation that flow meters are the least accurate way of determining when to backwash. I would still like to have one because I like doing things by the numbers I saw a link to My Pool Yard on another post (sorry don't know how to link) and it says all I need is my pipe size. I know I have 1.5 inch but it is the flexible stuff for above ground pools. These meters mention PVC. Would they or any other reasonably priced meter work with my set up? Thanks!