The previous discussion from months ago did not totally dismiss the saturation indexes but did explore the non predictability of a pool environment. Even after my discussion with Richard (chemgeek) I do feel there are merits to predicting the saturation index using his calcations. I can’t find his spreadsheets he created readily but he did some great work in prediction scaling and I would recommend using his calculations. Down and dirty answer. Lower pH and ALK may prevent the precipitation of calcium but may damage the heater if the heater core is copper.
Steve