our home water softener (made by kinetico) uses an ion exchange system that replaces sodium and calcium ions with salt ions (sodium and potassium chloride ions)
soft water isn't soft water if it has minerals in it
anyway read all about it here click on the hard/soft water part. You should find local system in your area (ask the neighbors).
I hope this does remove the hardness because we paid over a grand for it. (our white clothes stay white during washing) Last thing, if you get one, make sure it's connected before the outside water lines.