How to Increase Free Chlorine in Pool Water

You need to ensure that the level of free chlorine in your pool stays high enough to keep it sanitary and safe to swim in. Free chlorine levels in your pool should be at least 1 part per million (ppm) to kill algae, bacteria and other similar organisms that grow in it. If you determine by testing the water that your free chlorine level isn't high enough, you'll need to increase it to keep the pool sanitary.

Free chlorine keeps your swimming pool water clean.

Step 1

Determine the level of free chlorine in your pool by testing the water every day if you can, but test it at least two or three times per week. Reading the directions on the package will allow you to interpret the color, whether it's purple on a test strip or red in a test kit. If you find that your free chlorine level isn't at least 1 ppm, you'll need to take measures to raise it.

Step 2

Check any direct chlorination system you may use, whether it's a floating dispenser or an in-line chlorinator, to be sure it has sufficient chlorine in it. If it does, adjust its setting to increase the rate at which it dispenses chlorine to increase the free chlorine level.

Step 3

Adjust the voltage dial on a saline generator, if you use one, to a higher setting to increase the rate at which it generates free chlorine. The normal setting required to keep the free chlorine level at 1 ppm is 50 percent, but if you dial it up to 60 percent or 70 percent, it will generate more chlorine to raise your pool's free chlorine level. If your free chlorine continues to be too low, particularly several days after you run your weekly superchlorination cycle, try running the superchlorinator for longer than the usual 12 hours needed to maintain the free chlorine. Superchlorinating for up to 24 hours will also increase your pool's free chlorine levels and keep them up longer.

Step 4

Use your test kit or strips to test again within a few days of increasing your free chlorine to be sure that the levels have gone up, but also to make sure that you didn't overshoot the mark and exceed 3 ppm. If you find you did increase free chlorine to over 3 ppm, dial back the rate at which your chlorinator generates chlorine to bring it back down.