First, the honest part. "Salt-free water softener" is a marketing name: these systems do not soften. The hardness minerals stay in your water. What the media does (template-assisted crystallization, or TAC, for SpringWell and SoftPro; Scale Control Media for Aquasana) is turn dissolved calcium into tiny crystals that are less likely to stick inside pipes and heaters. SpringWell claims up to 95% scale prevention for the FutureSoft, SoftPro 99.6% for the Fortress. Neither figure comes with a certification on the product page.
So who should buy one? Households that mainly want to protect a tankless heater or new plumbing, cannot run a drain line, live where salt softeners are restricted, or simply refuse to carry salt. Who should not? Anyone who wants spot-free glasses, slick soft water, or has iron, manganese or hydrogen sulfide: the FutureSoft is rated for 0 ppm of each.
With our formula, the Aquasana salt-free conditioner ranks first: the highest stated peak flow (15.3 GPM), a 10-year media life and warranty, and an independent test of its scale claim, for $1,758. The SpringWell FutureSoft adds a lifetime warranty and a 6-month money-back promise at $2,100. The SoftPro Fortress costs $529 for 10 GPM, the cheapest way into salt-free by far, with a 1-year warranty to match.