New product to remove calcium hardness??

[Teapot1]

In Europe its often available in DIY stores as wood bleach. I haven't used it and after 20+ years of pool work in Europe, specifically France I haven't heard of it being used for removing hardness but I am not saying it wouldn't but adding as Chemgeek said early on phosphates would be very bad. If its Not a salt water pool you can use zeolite filter media, this is an ion exchange resin that will swap sodium for calcium. Once it has absorbed as much calcium as it can you replenish it with a salt water soak of the filter. Thats rinsed away and off you go again lowering your calcium.