As if inspired by the sea, a salt water chlorinator helps keep this stunning rim flow swimming pool fresh and sparkling clean all year round. Hand packed concrete construction lined with fiberglass.
Salt Water Pools Are from the Salt of the Earth
A simple ingredient has helped make pool care quicker, easier and more effective than ever before. Penny Swift asks the experts how it works.
“Salt water chlorination has become the most effective, most environmentally friendly method of pool cleaning.” Barry Menesis
More than forty years ago the salt water chlorinator, invented in New Zealand, was considered to be a space age device which promised to perform small miracles. It was viewed with some suspicion by the man-in-the-street – because it offered almost unbelievable benefits and characteristics.
In a nutshell, the experts said that a salt water pool meant minimum maintenance and low operating costs.
Today these little machines are commonplace and many pool builders install them as a matter of course.
The concept of a chlorinator combines science with nature. It uses salt which makes its own chlorine at a fraction of the cost of regular chlorine. The unit works in conjunction with the pool filter or a separate power supply. A salt cell is fitted to the pool plumbing system between the filter and the water outlet and a control unit is mounted next to the cell for easy monitoring and control of the pool water.
Once the chlorinator is operating, the water becomes slightly saline. This is not unpleasant and converts insist that it is in fact the most healthy form of chlorination, producing crystal-clear water which is constantly sparkling clean and healthy.
“The fact that the water is slightly salty makes it less irritating on swimmers’ eyes,” says Colin Rodell of Sun Salt Services, suppliers of pool salt to the swimming pool industry. “Just taste your tears and you will see why.”
Explaining how the chlorinator works, Colin says that when a suitable electric current is passed through salty water in a specially designed chlorinator cell, it splits the salt, liberating chlorine gas which dissolves in the water. This sterilizes the water and prevents the growth of algae.
“Freshly liberated chlorine is known as ‘nascent’ and is highly reactive, thus making it very efficient.”
Colin explains that as the chlorine is liberated, the sodium end of the salt remains in the water and makes the pool alkaline. It also raises the pH, so to counteract this, it is necessary to add pool (hydrochloric) acid. This immediately reacts with the sodium end to make salt.
In theory, this should mean that you should never have to add salt to the pool. However we all have to backwash our pools and so inevitably the salt is diluted. If the concentration of salt becomes too weak, the electrodes will not make enough chlorine and the system will not be effective.
The recommended salt concentration varies between 4 000 and 7 000 parts per million, depending on the chlorinator you are using. This means that you will need between 8lbs and 15lbs (4 kg and 7 kg) of salt per 200gals (1 cubic meter) of water volume.
“Using a good quality salt helps to prevent damage to the electrodes in the chlorinator,” says Colin. “Never use iodated salt.”
Having a salt water chlorinator does not mean an end to those regular pool checks. It is important the you check the pH of the pool water regularly and do not overdose the acid. Never reduce the pH below the recommended levels of 7,3 – 7,5. This is particularly important in marbelite pools as too much acid will eat into the marbelite coating.
A chlorine stabilizer is available and will help to prevent the loss of chlorine from the pool water. It should be added 40–60 parts per million or 2 oz (50 grams) for each 250 gals (1 cubic meter) of water volume.