07/21/2026
It's that time of the week 😎 Pool Tip Tuesday 🌊
Piggybacking off of last week with phosphates, we are going to talk about something that they can cause and is another leading problem we see with pools all year long, especially in the early and mid season; that being combined chlorine.
It is not widely known that we test for two chlorine values when we test water, as most common testing methods such as test strips or the two way test kits only test for "Free Chlorine." The other value is something called "Total Chlorine,"
Free Chlorine is the amount of "active" chlorine in your pool, i.e. what is actually working in the pool/spa to break down/kill bacteria and algae; while Total Chlorine is the amount of chlorine you have in your water in total, period. So when they are not equal, like your total chlorine being 3 but your free chlorine is 2 that means you have a "combined chlorine" issue.
What this means is that the active chlorine (free) is being bound in someway, most of the time by organic compounds such as phosphates, pollen, and algae. It is important to keep your chlorine levels even, because if your free chlorine is bound, it doesn't matter how much total chlorine you have, none of it is actually working to break down debris.
The methods for treating combined chlorine can vary depending on the cause. If you're having trouble maintaining chlorine in your pool, stop by for a free water test. We'll identify what's causing the issue and help ensure your chlorine stays active, keeping your pool clean, clear, and properly sanitized.
As always let us know if you knew this, if it was helpful, or if you have further questions!
