Depends on what area you live in and therefore the water supply for that area. *If you live in an area where the water is "hard", you will need to
a) "soften" it before it gets to your appliances ( by way of a water softener) OR
b) * use a water filtration system that releases an "anti -scaling" substances into the water before it gets to the appliances.
a) above effectively takes the scale producing substances (calcium etc) out of the water before it ghets to the equipment while b) instead stops the scale from coming out of solution & sticking to the inside of the equipment.
Thats kind of dealing with the problem from two opposite ends of the spectrum.
After that Im afraid you have to place yourself in the hands of the water business professional and trust his advice in recommending the correct scale inhibiting filter for your application.....sounds like youre on the right track.
All the above is stated without knowing exactly what machine or equipment you are wanting to "protect". For example, if it is one of the commonly available aluminium thermoblock machines, even if you feed it with either softened water or water that has come through a filter that releases anti-scaling agents.....you will still have the problem of the formation of aluminium corrosion in the thermoblock or boiler so you would still be wanting to run a cleaning / flushing cycle at arbitrary intervals....