Chlorine is a commonly used chemical to achieve satisfactory bacteriologicaland chemical purity in spas. It must be present in the ‘free’ form to killbacteria and oxidise organic matter derived from bathers. Provided the water isbalanced, chlorine levels of between 3.0 to 5.0mg/l are sufficient to maintainhealthy, clean water. A well managed chlorine treated spa will have no odourand levels of chloramines (combined chlorine) of less than 0.5mg/l. Combinedchlorine 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 adequatelyand gives rise to the ‘chlorine’ odour.
A traditional granular chlorine that is popular with spa owners as it givesdose rate flexibility. These granules are rapid dissolving makingpre-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 havelittle effect on the pH level of your spa water.