I have a total hardness test kit. Once scoop of powder turns it pink, and for every drop its 1 grain hard or 17.1 ppm. It turns blue as soon as I add the scoop.

My house water has a softner. My house water is 1 gpg or 17.1 ppm, hence my pool is the same. Thats my fill water.

I have never added any chemical to my pool but BBB from day one.