Ions are mineral salts dissolved in water, with a positive or negative charge. Some of these salts are hardness minerals that cause limescale. Removing ions from water (or neutralising them) is also called deionisation. The best-known form of deionisation, and the most widely used technique for filtering ions out of drinking water indoors, is ion exchange.
Devices that exchange ions are also called ion exchangers. The ion exchanger is installed after the water meter and contains a filter housing filled with ion exchange resin.
These synthetic resins are treated (ionised) so that ions bind to them. The resin is used in the form of resin beads in a water filtration system. Each type of resin is in principle ion-selective; for example, there are resin filters that are only effective against calcium, magnesium, iodine, nitrates, silicates or phosphates.
The most user-friendly ion exchangers are the so-called "cation-anion filters". They are fitted with so-called "mixed-bed resins" or "mixed-bed filters": a colourful collection of resins that remove all positive and negative cations and anions from the feed water, including calcium and magnesium. One reason why this is often used.
That's why the optimal ion exchanger contains a "mixed bed" of strongly acidic cation resin and strongly basic anion resin. After the cations present have been exchanged for hydrogen ions [H+] and all anions for hydroxide ions [OH−], a reaction takes place between hydrogen and hydroxide, leaving pure water [H2O]. Over time the resins become saturated or exhausted; they then have to be regenerated or replaced.
Please note: anything that is not charged is not held back by the ion exchanger and therefore stays in the water.
The resin H2Ot uses is of professional quality. As a result, it lasts up to 10x longer than standard resin, and it is a specifically charged bed designed to remove calcium and magnesium in our water softener. That's different for the systems that go beyond softening alone, such as ViruLEX and SorCA, which we also offer.
How it works in ZeNO
In ZeNO the water flows from top to bottom through the resin, which is enclosed at the top and bottom between two extra-fine 100 µm filters. This means all the resin is used. Conventional water softeners don't have these filters: they develop so-called 'dead zones', part of the resin that never becomes active. To soften sufficiently anyway, they use much more salt and water during regeneration. As a result, ZeNO uses up to 60% less salt and up to 66% less water than a traditional water softener. View ZeNO.