My friend has a 19000gal IG vinyl pool with a Zodiac DuoClear SWG, which uses the Nature2 cartridges. The owner's manual recommends CH of 200-400ppm but doesn't differentiate between vinyl and gunite. She doesn't have a heater. Why would the mfr want the CH so high? I called Zodiac to question this and the kid(sorry, but he sounded REALLY young:rolleyes: ) said she should keep the CH at 100-200. So naturally I'm asking the people I trust the most...YOU! TIA
Hal
