Working principle
In sodium ion exchanger in a certain height of sodium ion exchange resin as exchange agent. Top to bottom to water through exchange agent layer, the sodium ions exchange agent of the replacement water calcium and magnesium ions, make water got to soften. Reaction as follows:

Ca2 + + 2 NaR-CaR + 2 Na +
Mg2 + + 2 NaR-MgR + 2 Na +

The sodium ions exchange agent were gradually replaced by calcium and magnesium ions, when use after a period of time, will leak out of the calcium and magnesium ions, in out of the water hardness of the provisions of the value, namely stop running, regeneration. Regeneration will 5 ~ 8% salt water (or rare hydrochloric acid) from the next up through exchange agent layer. Salt solution of sodium ions and replacement of the exchange agent calcium and magnesium ions, making exchange agent get regeneration, restore its exchange ability. Reaction as follows:
CaR + 2 Na +-Ca2 + + 2 NaR
MgR + 2 Na +-Mg2 + + 2 NaR