Salt Water Chlorination
“Salt water chlorination has become the most effective, most environmentally friendly method of pool cleaning.” Barry Menesis
Thirty years ago the salt water chlorinator 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 sterilises the water and prevents the growth of algae. “Freshly liberated chlorine is known as ‘nascent’ and is highly reactive, thus making it very efficient.”
Adding salt 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 4 kg and 7 kg of salt per cubic metre of volume.
“Using a good quality salt helps to prevent damage to the electrodes in the chlorinator,” says Colin.“Never use iodated salt.” Maintenance 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 stabiliser 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 50 grams for each cubic metre of water volume.
The inventor Although chlorinators are now manufactured in various parts of the world, the salt water chlorinator is in fact an Australian invention. According to Barry Menesis, from Zodiac Pool Care, it all began in Len David’s back garden in the early 1970s.
An Australian scientist who wanted to improve the chlorination of swimming pools for greater safety, convenience and economy, Len decided to experiment with titanium electrodes. “Len started off working in his garden shed, testing his own pool water,” says Barry who has been in the pool business for many years and is an expert in salt water chlorination.
“When friends also wanted to try his new sanitising technique, he expanded to his garage. Not long after this the first Clearwater chlorinator was produced..” Numerous companies now manufacture salt water chlorinators worldwide, with varying degrees of quality and performance. Some systems also produce a small amount of ozone which add further sparkle to the water. “Sanitising swimming pools with salt water chlorination has become the most effective, most environmentally friendly method of pool cleaning,” says Barry.
Article sourced from the NSPI website: http://www.nspi.co.za/ with their full knowledge and permission.
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