mbUofL
Member
I also have a whole home softner which is used for fill water for what its worth.Calcium stays in the water for good. If someone has very hard fill water that's been used to replace evaporated water (which leaves the calcium back in the pool), CH increases over time. But if there is a leak and you replace calcium containing water with fill water (at a different CH level), then the pool CH will drift towards the fill water CH.
Appreciate your insights here. Might be worth me testing fill water.