3 Things to Know About Combined Chlorine

Combined chlorine equals total chlorine minus free chlorine Measure free chlorine first, then total chlorine. Subtract free from total to get combined chlorine, also known as chloramines.

Keep combined chlorine below 0.5 ppm Levels above 0.5 ppm mean your pool needs shocking. High combined chlorine causes that locker room smell and burns your eyes.

Test combined chlorine regularly Most pool owners skip this step. Don’t be one of them—it’s the only way to know if your pool needs treatment.