There are many products that you can buy claiming to be no salt water softeners for people living in hard water areas. Hard water can not only taste unpleasant but can cause staining in your laundry, cost you money by having to use greater quantities of detergents not to mention harming water heaters and pipes with due to them becoming clogged up with lime-scale. In these more environmentally aware days using ever increasing amounts of salt to counter the problem is seen as a less attractive proposal compared to one of the more sophisticated no salt water softener systems.
The Chemistry Behind Them
No salt water softeners are actually based on proven scientific principles associated with hard water. All water, unless purified by distillation, will have some salts dissolved in it. These are mainly salts of the metals; calcium and magnesium, along with manganese and iron (Ferrous) plus a few more.
However, only one of these salts is the real cause of the problem and that is calcium bicarbonate. The chemical formula for calcium bicarbonate is Ca(HCO3)2, the only reason for showing that is because it only exists as an aqueous solution, or when dissolved in water.
If a solution of calcium bicarbonate is allowed to dry out, water (H2O) and carbon dioxide (CO2) are released leaving calcium carbonate (CaCo3) and it is this solid – calcium carbonate, that we refer to as lime scale.
As an aqueous solution of calcium carbonate dries out the calcium carbonate is precipitated out of the solution, it will then start to adhere, attach, itself to any surface it comes into contact with forming a build up of lime-scale.
To prevent the buildup of lime-scale in water systems you need to offer the calcium carbonate an alternative surface to stick itself onto, rather than the pipes or heating elements in the water system. The technical term for this is to offer it alternative sites for nucleanation, this is exactly what a no salt water softener will do.
Also known as physical water conditioners, no salt water softeners encourage the lime-scale particles to remain suspended in the water. Once formed as a particle suspended in the water it will not revert back to calcium bicarbonate and risk the whole cycle starting again. The individual particles are then simply ‘washed’ away with the water when it eventually leaves the domestic water system.
How Magnetic/Electrolytic No Salt Water Softeners Work
An electrolytic no salt water softener will often be a zinc dosing mechanism. When released into hard water zinc will seek out carbonates to form zinc carbonate, fortunately zinc carbonate crystals have a similar shape to calcium carbonate – which will then nucleate, or seed and attach itself, onto the zinc carbonate. The net result of this is that the calcium carbonate (lime-scale) remains suspended in water and gets washed out of the system.
Of course you only want a little zinc released into the water at a time, so the water is passed through a zinc anode which deliberately corrodes into the water. The zinc is released by the action of water flowing through a magnet, which generates tiny DC currents by electro-magnetism, so the speed of flow of water past the zinc anode determines the amount of zinc released. Or, in other words, you have no need to be concerned about an artificial build up of zinc in your water supply.