Chlorine is a beast – it kills things. Discovered in the early 1800’s it’s been used in many industrial processes, to sterilize potable water and finally, used to sanitize swimming pools.

“Chlorine basically tears apart a germ, shredding its cell membrane and proteins.”1

But too much of a good thing can be, to put it simply, bad.

Too Much Chlorine

You may not realize you’re using too much chlorine in your pool until:

  • You notice swimsuits bleach out quickly

  • Swimmers complain about itchy skin

  • People in your pool have red eyes

  • Someone says, “I love that chlorine smell!”

Worse, your pool surfaces may become faded or pitted. While you may think that’s to be expected, that’s not true and you can avoid that.

Maintaining the right chlorine level can be tricky. Keeping the chlorine level within ideal ranges isn’t easy, and most pool owners don’t realize the huge downside of using too much or too little before they encounter trouble.

It may seem obvious, but testing your pool water regularly is always the best practice. That way you’ll know what your chlorine levels are and can make adjustments before the water becomes a problem.

Here are a few tips if you are over-chlorinating:

Tip #1: Check Your Dial Setting

If you use a chlorinator or salt generator turn the dial down.

If your pool water is greatly over-chlorinated, turn the device off until the level comes down to your desired number (between 1.0 and 3.0 ppm typically).

To help find the correct setting that will maintain that chlorine level, adjust only one setting per day, and test the water after 24 hours to see the effect.

Once you find the correct setting do not alter it. When abnormal conditions arise (pool party or a lot of rain) that’s the time to shock the water.

Tip #2: Cut Back On Amount Of Chlorine Used

If you  use a chlorinator or floater, the setting may not be enough to regulate the output properly. You may need to resort to filling the unit partially full.

Since these units often wet all the chlorine at once, it is difficult to regulate with exactness.

twelve white chlorine pellets scattered in front of a blue pool in the background.

The more chlorine that is wetted, the greater the output. If you’re putting chlorine pucks in the skimmer by hand or using liquid, cut back on the amount you add or the frequency.

Tip #3: Make Sure Your Water Is Properly Balanced

Water balance is critical to proper sanitization.

However, if the pH is higher or lower than 7.2-7.8, that could cause chlorine to become ineffective.

In a pool where the pH level is below 7.2 chlorine dissipates much more quickly, which translates into a larger chemical expense and more time spent adding sanitizers to your pool.

On the other hand, if the pH level is higher than 7.8, chlorine loses its ability to sanitize the water, forcing you to use more chlorine to achieve the same chlorine concentration as a pool with a balanced pH level.

For example, at a pH of 8.2, chlorine concentration can only reach 15%. This means that if you only had to add one dose of chlorine at a pH of 7.2, at a pH of 8.2 you would need to add 5x that amount to achieve the same chlorine concentration.

Keep pH within the ideal 7.2 -7.8, it can save you from troubleshooting!

Tip #4: Evaluate Pool Use

If the pool isn’t used very often, then the need for chlorine is lessened.

If this is a temporary situation, such as during the spring when temperatures are cooler, cut back on the amount of chemical you’re dispensing, and your pump run time until your normal use pattern returns.

Tip #5: Consider Shortening Your Pump Run Time

Very few pools are used enough to require a 24 hour circulation, yet many pools run their pump that long.

Any inline feeding device continues to dispense chlorine every minute the circulation is running. To cut back on how much is dispensed, consider adding a timer to your pool and cutting the circulation time (see calculating pump run time).

Tip #6: Check The Expiration Date On Your Test Strips Or Kit

Most test strips and testing reagents last only 12 to 18 months. Look for the date stamp on your test strip bottle or kit. After that date, they may not register readings properly.

Dry your fingers and hands before grabbing a test strip. Wet fingers or hands that reach into the test strip container can easily contaminate the strips, which will shorten their life even further.

Frog test strip bottle. The over bottle is white, but the colors on the side are shown to hold comparison to the actual test strip after dipping it in the water that you are measuring.

Tip #7: Remove The Pool Cover And Let The Sun Shine In!

Another way to reduce chlorine: remove the pool cover and leave it off for a while; sunlight’s UV rays burn off chlorine and can thus lower chlorine levels in relatively short periods of time.

Use a test strip or test kit to test frequently so all your chlorine doesn’t dissipate before you realize it!

Tip #8: Drain Some Water And Refill

If time isn’t an issue, drain and refill some of the pool water to reduce chlorine in the pool.

However, this process may have an impact on your pool’s chemical balance, so you’ll need to test and rebalance your pool water to ensure it’s within ideal parameters:

Free Chlorine: 1.0 – 3.0

Total Alkalinity: 80 – 120 ppm

pH: 7.2 – 7.8

Total Hardness (also known as Calcium Hardness): 200 – 400 ppm

Having trouble maintaining consistent chlorine levels?

Consider whether or not you’re using the right sanitizing system.

If you’d like to maintain a consistent chlorine level and even better, use much less chlorine, consider Pool FROG®, it cuts chlorine use in half; it works with FROG Minerals to kill bacteria 2 ways, with a low level of chlorine and minerals. Plus, it delivers a consistent chlorine level.

Most pool owners keep their chlorine level between 2.0 – 4.0 ppm

When using Pool FROG, ideal chlorine levels are 0.5 – 1.0 ppm. The reason so much less chlorine is needed is that chlorine works together with FROG Minerals to kill bacteria. Only FROG offers this complete sanitizing solution that’s registered with the Environmental Protection Agency.

When chlorine is kept at a low 0.5 – 1.0 ppm level:

  • Swimsuits stay brighter longer

  • Water feels softer

  • Skin, and hair aren’t irritated

  • There’s much less “chlorine smell”

  • Pool surfaces are protected from chlorine’s harsh effects

If you have a FROG system, we have solutions for over-chlorination. Check out this video:

You can also find out more on the FROG Water Care App. Download it for FREE if you haven’t already at the App store or on Google play. You can get help for pool, hot tub or swim spa water care, watch videos and more 24/7.

1. Michele Hlavsa, chief of the Centers for Diseases Control and Prevention’s Healthy Swimming Program


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