Swimming pool saltwater chlorinators are often described as being self-cleaning or reverse polarity. These descriptions are used to show that the chlorinator cell needs less manual cleaning.
The descriptions “self-cleaning” and “reverse polarity” refer to the use of the same technology. The term “self-cleaning” can though be misunderstood to mean “never ever needs cleaning”, which is definitely not the case.
Swimming pool saltwater chlorinators all rely on applying the principles of electrolysis. There are many uses for electrolysis in the modern world from wet cell batteries to product etching to chemical reactions. In all cases, a DC electrical current is required as well as a conductive fluid allowing the current to pass between a pair of submerged anode and cathode.
In swimming pool chlorinators, the DC current is supplied by the Power Supply or Chlorinator Controller. While this device may have timers and various other controls, its primary role is to take mains AC current and convert it to low voltage DC current, then supply that current to the chlorinator cell.
The chlorinator cell is where the electrolysis occurs. The cell consists of two equally numbered sets of conductor plates made from high nobility metal, that is metal less likely to corrode. These plates are housed inside an enclosure, usually made from a high strength durable clear plastic.
By passing a low voltage DC current across the plates in a mild salt solution, such as the water in a saltwater swimming pool, a chemical reaction occurs releasing the bond holding sodium (Na) and chloride (Cl) together in the NaCl or pool salt. The chloride in turn becomes chlorine – our primary sanitiser in most swimming pools.
The chemical reaction does leave a scale, usually calcium, on the cathodes and generates a small amount of hydrochloric acid at the anodes. By regularly switching the polarity using Reverse Polarity circuitry – anodes become cathodes and vice versa – the need for regular manual cleaning is dramatically reduced. What used to be a cathode now becomes an anode and produces hydrochloric acid. This hydrochloric acid helps remove the mineral scale from the now anode cell plates.
This process is sometimes called self-cleaning, but that can be a little deceptive. The cells will still require occasional cleaning, usually in a mild cleaning solution.
Davey use the description Reverse Polarity as this does not mislead consumers as to the occasional need for manual cleaning of cells. The basic technology of Reverse Polarity and self-cleaning is the same.