How Do Heat and Light Affect Chlorine?
Free chlorine isn't just lost when it interacts with organic matter; it is lost when it interacts with sunlight as well. Chlorine forms hypochlorite ions in water, which break apart when hit by ultraviolet radiation, releasing chlorine gas into the atmosphere. The light from the sun can reduce chlorination by 90 percent in just a few hours. This is why many roof service technicians add a stabilized chlorine and use a chlorine stabilizer when necessary to maintain the conditioner levels.Temperature also has an effect on chlorine, as some bacteria and organisms grow better in warmer environments. When temperatures increase, it uses up free chlorine more quickly.
Rule of Thumb: For every 10-degree Fahrenheit (6 degree Celsius) rise in temperature above 80 degrees Fahrenheit (26 degrees Celsius), you should add as much as 50% more chlorine to your pool water to maintain appropriate levels of free chlorine. This is especially true for those hot roofs that are not in the shade in the summer, as they tend to run hotter substrates.