Chlorine is a commonly used chemical to achieve satisfactory bacteriological and chemical purity in spas. It must be present in the ‘free’ form to kill bacteria and oxidise organic matter derived from bathers. Provided the water is balanced, chlorine levels of between 3.0 to 5.0mg/l are sufficient to maintain healthy, clean water. A well managed chlorine treated spa will have no odour and levels of chloramines (combined chlorine) of less than 0.5mg/l. Combined chlorine is created as a result of a reaction between free chlorine and organicmatter and is a mixture of Monochloramine, Dichloramine and Nitrogen Trichloride. The latter is mostly produced when the water is not being treated adequately and gives rise to the ‘chlorine’ odour.
A traditional granular chlorine that is popular with spa owners as it gives dose rate flexibility. These granules are rapid dissolving making pre-dissolving and application easy. The granules have a pH value of about 6.0– 7.0, which is fairly close to the ideal spa water pH level and so will have little effect on the pH level of your spa water.