How to test for chlorine levels in your pool? 

How to test for chlorine levels in your pool? 

Chlorine is a pool's most essential and crucial element of water chemistry. 

It acts as a sanitizer and keeps the water free of any microorganisms. 

Maintaining its optimal levels is a vital element of pool maintenance; to do that, you need to check the water's chlorine levels regularly.  

Follow this guide to learn the why, when, and how of testing pool chlorine.


How to test for chlorine in your pool

There are three methods to test chlorine levels in your pool, and each of them has its pros and cons:

  • Pool Test Strips: Easy and quick but inaccurate.

  • Pool Test Kits: This takes time and effort but is highly accurate.

  • Digital Pool Monitors: fast and easy. Costly upfront, but a guarantee your water will never go awry, and will pay itself over several times. 

Now, let’s look at the step-by-step process of chlorine testing using a pool test kit.

Remember to choose equipment that measures free and total chlorine for the best results. Check out our detailed article on free vs. total chlorine to know more.

For this example, we will use the Taylor pool test kit

  1. Take the empty testing vial and rinse it with pool water.
  2. Refer to the user manual of your kit and fill the vial with the appropriate amount of pool water.
  3. Add a couple of measured scoops of DPD powder into the sample. 
  4. Mix the liquid reagent drop-by-drop until the color of the water changes. 
  5. Multiply the number of drops added to the sample and multiply it by 0.20. The resulting number is the chlorine level of pool water. 

Pro Tip: You can use our Sutro Pool Monitor to receive the chlorine level readings three times a day on our mobile app. Plus, you also get detailed recommendations on how to make adjustments. 

What is the optimal range for chlorine in a swimming pool?

The optimal chlorine levels in a swimming pool should be between 1 and 3 ppm. The stories of total chlorine should be equal to or slightly less than free chlorine, and the combined chlorine should always be 0 or less than 0.5 ppm.  

How often and why should you test chlorine in your pool water?

You should check your pool's chlorine levels at least twice every week. This frequency can increase to three times a week during the summer months. Additionally, checking chlorine levels is important after events like a rainstorm, heavy pool use, change of water, and the addition of fallen leaves. 

Too low chlorine levels in pool water lead to unsanitized water with algae growth and bacterial buildup. It can also lead to skin infections, cloudy water, and other chemical imbalance in the water. Similarly, very high chlorine levels can lower the water's pH levels, leading to irritation of the lungs, eyes, and skin. 

For better monitoring, consider using a smart water monitor. By getting a Sutro pool monitor your chlorine levels will be read 3 times per day, allowing you to have cacth any issues fast, and maintaining high balanced water quality in your pool all season round.  

Can swimming pool chlorine test kits go bad?

Yes, the chemical reagents in test kits have an expiry date that is usually one year from the date of manufacture. You can refer to the packaging label of your test kit to check the best-before date.

When to test pool water after adding chlorine?

The general rule of thumb is to wait 24 hours after adding chlorine to the pool, as it allows the chlorine to circulate properly. However, you can check the chlorine levels after about eight hours and use the pool if the water balance is restored.  

How to test chlorine in saltwater pools?

The process is the same as testing chlorine in regular pools. You can use a pool test kit or digital monitor for this.


Chlorine is essential for pool water because it acts as a sanitizer and kills bacteria and microorganisms. It keeps the water clean and prevents many problems, such as algae growth and skin-related hazards. The best method to measure chlorine in a pool is to use a pool test kit or a digital pool monitor. Chlorine must be checked and adjusted at least twice weekly for proper maintenance. 

Back to blog