I got a new 24' pool installed last year and the installers did not add any valves to the flexible hoses. I will hard plumb before re-opening this year. I plan to use union/ball valves and sch 40 PVC pipes. I know I need a valve between the skimmer and pump so I can clean the pump basket but I'm unsure if I need a valve on the line from the sand filter to pool return or if I need one between the pump and sand filter. Please share where your valves are located and how/when you use them.