As a guide, a pool will lose approximately 1/3 of its pool water each year. Therefore salt will need to be topped up to maintain the recommended level. This normally equates to about 100Kg (4 bags) or 220 lb (5½ bags) per year.

In Australia, a 25Kg bag is common.     In the USA, a 40lb bag is common.

Salt is not lost by the process of chlorine manufacture (electrolysis) or when water evaporates. It is lost, only by backwashing, pool overflow (heavy rain), splash out or a leak. The average pool loses about one third of its pool water each year.

How do I know when my salt level is low ?

1. The chlorine output will drop. During summer time, with the right salt level and a water temperature of 20°C (68°F) or above, the Watermaid WM10 Power Supply should show above 75%.  Or for a Watermaid WN934A Power Supply, the meter should show above 12 amps. The salt level can be checked either by using a hydrometer or by taking a sample of the water to a pool shop. If the salt level is correct and there is still a low reading on the chlorine production scale, check the age and condition of the Cell.

2. Chlorine tests will show low or zero readings

3. The pool may not be in its normal crystal clear condition.

The best type of salt to use is Fine or Coarse Rock Sea Salt (NaCl) that is specifically recommended for use with salt water swimming pool chlorinators. This type of salt contains the least amount of impurities and is normally sold at pool shops, hardware stores and supermarkets.

Potassium Chloride (KCl) can be used instead of the normal Sodium Chloride (NaCl), however it is more expensive.

The type of salt that you do NOT want to add to the pool is salt that contains a free flowing agent (containing Sodium Meta-Silicate). The use of this agent will cloud and foul up your pool.