How does salt water electrolysis work?

The electrolysis cell uses salt as a raw material and produces chlorine from it:

Salt is chemically known as sodium chloride (NaCl) and is made up of the two elements sodium and chlorine. When salt is dissolved in water and an electric current flows through this solution, the sodium chloride is split back into its two components. The sodium immediately reacts with the surrounding water (H2O) to form sodium hydroxide. The sodium hydroxide forms a salt again with the chlorine: sodium hypochlorite. This creates a hypochlorite solution in the pool, i.e. slightly salty water that is also antiseptic. This oxidises any organic material that gets into this alkaline water, ridding the water of viruses, bacteria and other pathogens. The result is clean, crystal-clear water.

And what happens to the liquid chlorine?

The liquid chlorine in the form of sodium hypochlorite releases its oxygen. The compound decomposes within a few hours to turn back into salt. The cycle closes and the electrolysis process starts all over again.

What does this mean for pool salt requirements?

Salt does not volatilise. Therefore, the salt concentration remains almost constant. The salt content changes in hot weather and intense sunlight, i.e. when water evaporates, or in heavy rain. In such cases, top up with water or pool salt to restore the required concentration. You can find out how high the salt concentration in the pool water should be for optimum electrolysis in the manufacturer's instructions for your salt electrolysis cell. Make sure you pay attention to this!