A salt free water softener system will do exactly as it says – soften your water without having to pass it through salts. Salt free water softeners work by preventing the hard scale that sticks to, and can be so destructive toward pipes, valves and other water system components. They do this by changing the dissolved ‘hard’ minerals in the water into harmless and inert, or inactive, soft scale particles.
These softer particles will remain in the water, but are suspended in it rather than dissolved, meaning that they will harmlessly pass through the water system and down the drain – without involving any ecologically damaging and harmful caustic salts.
Although one of the more expensive no salt water softeners, and one that requires regular maintenance, cathodic water softeners are very efficient. The technical term for these units is biostats, where an electric current is sent through the water whilst it is a special chamber. The chamber has an anode of an iridium coated titanium mesh whilst the cathode is basically a steel wire brush.
At the cathode a high pH is generated that causes the calcium bicarbonate, which causes the hardness in water, to precipitate out as calcium carbonate, which is what causes the lime-scale – on to and around the cathode.
Particles forming on the anode are simply flushed away later. However, and this is the really significant bit, they also become nucleation seeds for other calcium carbonate particles. This means that when the water is heated they encourage the ‘scale’ in hard water to cling to them, rather than to the pipes or heating elements.
Variously called electronic or electrolytic water softeners these work by passing an electric current through wires either wrapped around the outside or on the inside of a water pipe, at ninety degrees to the flow of the water. The wires could be a ferrite ring on the outside or a copper wire coil inside the pipe. The passage of electricity through the coil produces an electromagnetic effect that disrupts the ions present in the water.
Here ‘ions’ are the charged particles that constitute the hardness in water. This disruption leads to an increase in the willingness of the particles to become fixed to nucleation seeds, making it easier for them to be flushed away. Prolonged use of such a system can even result in existing lime-scale in water pipes being removed, as these charged ions pass over it.
Anodic water softeners are also sometimes referred to as electrolytic ones; these systems often use a zinc dosing technique. Hard water is caused by calcium bicarbonate and lime-scale by calcium carbonate. By passing hard water over a zinc source, zinc carbonate will be formed, this has the ability to trick calcium carbonate into joining on to it, thinking that it will be forming a larger particle of calcium carbonate. This is the process of seed nucleation mentioned above.
In doing this, the calcium carbonate cannot then attach itself to water pipes or heating elements – and the buildup of lime-scale is prevented. These systems are known as anodic or electrolytic ones as it involves zinc being released into the hard water when the water flows through a magnet producing tiny electric currents.