I've posted in the past with questions about how necessary it is to maintain Calcium Hardness in Vinyl Liner pools. The responses I received essentially said that it wasn't necessary to worry about Calcium Hardness in Vinyl Liner pools. Recently I learned a little bit more about corrosivity, and the Langelier Saturation Index. I spent some time creating what if scenarios with an online LSI Calculator and it seems that Calcium Hardness plays a pretty significant role in preventing corrosivity. So I'm wondering if I am misunderstanding what I was told in the past, or if my understanding of the LSI and how it applies is wrong. To be clear, the issue is not how it will effect the liner, but how it will effect metal parts, such as copper heat exchangers in heaters.