I see a lot of posts and recommendations on here that say CH levels do not matter in vinyl liner pools. I understand that it will not affect the liner itself. I am curious though about the effects of a low saturation index on pool heater exchangers and cement pool decks. Many other sites suggest that a saturation index below -.3 can be corrosive and cause pool deck pitting and metal corrosion. The holy grail Taylor water test kit even comes with a saturation index wheel. So why does everyone on here say not to worry about it?