Over the past couple of years, many companies have been advertising “No-salt water softening systems”. This is, in fact, very misleading. We sell units like this too – but almost entirely for the commercial market where the water is in closed loops and not exposed to air. We thought it needs to be clear what these systems offer.
These units can be more accurately called; “scale prevention units” – not softeners. These salt-free scale prevention systems will not do the following:
Reduce mineral build up on dry surfaces such as glass from the dishwasher and shower doors.
Make water easier on skin and hair
Reduce the amount of soap used in washing machines, dish-washers and the shower.
What these systems will do is prevent scale buildup inside hot water tanks and household plumbing.
When these units first came on the market we were very excited. Water softening has essentially (despite increases in efficiency) been exactly the same for about 100 years. So we installed many in peoples homes. Unfortunately we were very disappointed with the results (as were my customers) and we had to remove the units and replace them with conventional softeners.
The problem: These systems use a technology called "Template Assisted Crystallization" which, in a nutshell, means that hardness molecules cling to one another and grow larger. The net effect is that the hardness does not precipitate to form scale inside piping and hot water tanks -  this makes these units ideal for closed water loops (such as radiators). However, once the water comes out of the pipes and it’s exposed to air, the hardness all precipitates at once - essentially forming a "sludge" - which then shows up on shower doors, fixtures, dishes, etc. Definitely not a good thing.
All this is to say that despite that we carry these units we do not recommend them at all for residential use. And (in our opinion) nor should anyone in my industry.