Ask Don: Do I need to add more Chlorine to my pool when it gets hotter?
Answer: You should test your water, or bring it in for a free test more often in the summer. You may need to add more chlorine. The temperature doesn’t matter as much as the direct sunlight. The kind of chlorine we add to sterilize pool water is affected by the sunlight. In a chemical process, the ultra-violet rays begin to degrade the chlorine in the water.
The degradation can be slowed down when you add a stabilizing agent such as cyanuric acid. The pH should be between 7 and 8, because if it is less than 7, the chlorine can disappear rapidly. Chlorine needs to be between 1 and 3 parts per million.