I'm still restoring this old hybrid pool. It is 20x40 somewhere around 35,000 gallons i believe. I have 2 skimmers, 1 main drain, and 2 returns. All of which are 1.5" sch 40 pvc. Looking to replace the pump and filter and add a natural gas heater to the pad. The current filter is a cartridge filter but I'm not sure of the state of it. Any recommendations on plumbing the pad and what equipment would be best?