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How to Interpret Pool Chlorine Readings


pool chemicalsNo one wants to get red eyes or swimmer’s itch from taking a dip in a pool. These nasty side effects can occur when your pool doesn’t have enough free chlorine to do its job. It can also happen when the water is too acidic for the chlorine to be effective. Learning how to correctly interpret pool chlorine readings will help you maintain your pool water’s pH and proper chlorine levels.

You can pick up chlorine and pH testing strips from your local pool supplier, big-box store or online. Chlorine home testing strips either measure “free chlorine” or “total chlorine.” Many people believe that these two terms are interchangeable, but they are not.

The way that chlorine eliminates harmful bacteria and contaminates is by chemically reacting with them. It essentially breaks down the cells of contaminates rendering them neutral. After a chlorine particle has done its job, it is no longer active or free. This is called “combined chlorine.” A reading of “free chlorine” tells you how much bacteria-fighting chlorine is left in the pool. A reading of “total chlorine” includes all chlorine—combined and free—in the pool.

When you test the chlorine levels, there should be 1.0 and 3.0 parts per million (ppm) of free chlorine per 75,000 gallons of water. If it is less than that, add 1 ounce of chlorine for every 75,000 gallons of water or 0.013 ounces per 100 gallons of water to increase it by 1 ppm. You can find helpful chlorine calculators online to give you the exact amount of chlorine to add to your pool if you have trouble doing the math on your own or want to check your calculations.

testing pool chlorine levelsIf your pool has a strong chlorine smell it is a sign that there isn’t enough free chlorine left to do its job. While a lot of people think this means there is too much chlorine, it means the opposite. To get rid of the smell, you will need to do a shock treatment. A shock treatment is a big dose of chlorine that quickly kills large amounts of contaminates.

Checking the pH of the water is also critical because chlorine is not as effective in acidic water. Pool water should have the same pH as human tears between 7.2 and 7.8. If the pH of the water is higher than this, you can bring it down by adding muriatic acid to the water. The best way to do this is by adding it to the deep end with the pump running to help circulate it. Wait six hours before testing the water again or adjusting it further.

Still confused or nervous about maintaining your pool water’s pH and chlorine levels? Give us a call! The pool technicians on our team at Pool Works will be happy to help you keep your pool water healthy. We serve residents throughout Polk County Florida. We can help you keep your pool sparkling clean.

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