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Adding Chlorine to Swimming Pools
It is generally recommended that home swimming pools are sanitized by the daily addition of a chlorine compound.
When using liquid chlorine or dry chlorine, it is customary that either the chlorine is added manually, on a daily basis, or perhaps may be fed into the swimming pool by some form of dosing pump.
When liquid or dry chlorine compounds are added to the swimming pool, there is usually a residue left over, after the active ingredient, chlorine, comes out of its compound to do the sanitizing work. In simple terms, the residue from liquid chlorine is salt (sodium chloride) and the residue from dry chlorine is calcium hydroxide. These residues stay in the pool water and build up over years.
Experimental work was conducted by several companies in a few countries in the early 1970s, whereby some primitive techniques were developed to produce chlorine in a miniature "chlorine factory" adjacent to the swimming pool filtration system. It was intended that the chlorine produced would somehow be injected under pressure, or otherwise added to the swimming pool water.
Two basic techniques were tried:
The addition of salt to the swimming pool water, and the electrolysis of this salty solution either by an electrode hanging in the water, or by electrodes fitted within the PVC pipework at the filtration system.
The generation of chlorine gas in a special vessel filled with concentrated salty water, and the collection of the chlorine gas for injection directly into the swimming pool water re-circulation system.
The first-mentioned technique became the dominant technique, being safer and easier to install.
These early salt water chlorinator designs were modified and improved to the extent that the salt water chlorinator is reliable, economical and effective. After 20 years of constant development, the technique has become standard practice for the Australian pool equipment industry. In the US, salt water chlorination is very quickly being adopted as the sanitation method of choice by pool builders and service professionals across the country.
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