In this article we provide some definitions that pool owners need to know when using chlorine as their primary sanitizing agent. When chlorine reacts with water it forms hypochlorous acid which is a highly effective sanitizer. Unfortunately chlorine also reacts with nitrates and ammonia to form unwanted pool chemicals called chloramines. Chloramines can irritate in high quantities and are responsible for the “chlorine like” smell than can hang over busy pools. Chlorimaines also are not effective sanitizers so need to be regularly broken down as part of a pool shock treatment routine.
Most pool experts suggest a weekly pool shock treatment during the summer months when the pool is being most heavily used. The shock treatment removes the chloramines from the water (by taking the pool water to a chemical point called breakpoint oxidation) and increases the levels of free chlorine (uncombined chlorine) in the pool. Free chlorine should be kept with the range of 2.0 to 4.0 ppm (parts per million) while chloramines (combined chlorine) should ideally always be below 0.02ppm. Combined chlorine levels are measured by subtracting the level of free chlorine from the total chlorine measurement. Non chlorine shock treatments are also available.
Chlorine is available in liquid, tablet and powder form. While liquid chlorine is more expensive and has a shorter shelf life, it is a sensible choice for pool owners with sensitive pool surfaces as there is less risk of bleaching. When purchasing chlorine keep a close eye on the available percentage of chlorine offered by different products and brands. A cheaper product may require higher dosages if the available percentage of chlorine is very low, a factor that will remove any cost savings that were made at the time of purchasing.
Chlorine pool owners know that the pH of the pool water needs to be monitored carefully to ensure that the chlorine remains effective. Recommended pH levels for chlorine pools are between 7.3 and 7.8. If pH is allowed to rise to 8.0, for example, the chlorine will only be 1/5 as effective.