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The Beginner’s Guide to Pool Water Testing

May 25, 2022

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Summertime means spending time by the pool. And if you are a pool service technician, that also means doing regular water testing to ensure the collection is safe for swimmers. This guide will teach you the basics of pool water testing to keep your clients’ pools in perfect condition.

Instant pool water testing

Pool water testing is an essential skill that pool service professionals must have in their arsenal. There are different ways to identify the composition of pool water, and listed below are some tests that give instant and precise results.

Pool water testing strips

Pool test strips provide instant and accurate results for the pool water. Select a product compatible with your water type—chlorine or bromine pools, saltwater, etcetera; make sure to shake excess moisture from the testing strips to avoid cross-contamination! For best accuracy, always compare colors within 15 seconds after wetting. Even minor delays can lead to errors when determining what’s wrong at first glance.

Because these pool test strips are cheap and reasonably accurate, many pool service professionals choose to include them in their go-to kit.

Liquid testing kit

A liquid pool water testing kit is the most accurate method for testing your pool water at home. The more careful you are with the reagents provided, the more precise your results will be. Generally, this type of test kit comes with preloaded reagents that can test for chlorine and pH levels in the water.

Your kit should contain: OTO (Orthotolidine) to test chlorine levels and phenol red for testing pH. Make sure to do the test on a white surface to view accurate results. When collecting the water sample, dip the container 12-18 cm deep. Following the instructions below will get you the results of your swimming pool.

  1. Add the collected water to both sides of the measurement jar.
  2. Add the required OTO drops to the chlorine side and phenol red to the pH side.
  3. Place a white paper behind the kit to view the right results:

The higher the pH, the brighter will be the red color.

When the chlorine is taller, the yellow color will be more pronounce

    4. Use the included chart to interpret the level of chemicals found in the water.

    Human error is intermittently the cause of miscalculated results, so exercise caution while adding reagents to water. Else, you may end up with skewed results.

    Digital pool water testing kit

    Digital pool testers will give you more precise and valid results; you will not need to refer to an included chart to interpret results. They are a bit more expensive, but a good investment in the long run.

    There are various brands available, and each is a little different. While some digital testers make your job easier, ensure to select the suitable variety for your pool to complete the job easier.

    At-store pool water testing

    Although most pool service professionals use this as a last resort, you can also collect water from the pool and send them to a local store to check the chemistry. While this is not usually the first option, it is handy for determining accurate results should there be any question about a customer’s pool.

    Chemicals in pool water

    Other than chlorine and pH, some chemicals affect the pool water chemistry. You can test for these chemical levels in the water once or twice a month.

    Alkalinity: Maintaining the alkalinity of pool water is essential. An increase or decrease in intensity will affect the swimmer’s health.

    Copper: A difference in your pH factor means the levels of copper may be high in your water. Make sure to check for copper levels in the pool water if there is a difference in your pH levels.

    Iron: Testing for iron is also equally important, as an increase would lead to rust formation in your pool equipment.

    Calcium: A change in calcium level will cause the hardness of the water, and a layer of sediment will be formed.

    What is cyanuric acid?

    Cyanuric acid is a water protectant. Adding this to your pool will protect you from the evaporation of the sanitizers from the sun and keep the sanitizers safe. But too much of this chemical will reduce the chlorine activity in your pool.

    Reasons you should clean the pool

    You would customarily be loading the pool with chemicals while closing the pool for winters. When you re-open the pool, it must be cleaned immediately. Typically, checking the pool intensity is essential, as it would tell your what invisible chemicals are doing in your pool. Checking for the chemicals will allow you to know the substances you should be dealing with for pool maintenance.

    When to check the pool?

    Frequent checks of your pool water for pool maintenance would ensure the safety of your pool environment. You can check the pool once a week for pH and chlorine. Based on your pH acidity, you can also check for cyanuric acid and calcium hardness once a month. Other times of roll-call on containing the pool water would be:

    • After a thunderstorm
    • After a pool party
    • After any weather changes
    • After refilling the pool
    • After the sighting of color change or cloudiness in the pool
    • Before starting any water treatment


    The time for pool maintenance is here. With the sun getting hotter each day, while you prepare your testing kit, think about hiring a professional to stabilize your pool if there are any variations in the value. A bi-monthly or quarterly pool cleaning is more effective in keeping your pool clean.

    Timely pool cleaning will ease your mind. Talk with your professional cleaner and set up a regular, ongoing pool maintenance schedule.


    Picture of Shivasankari Bhuvaneswaran
    Shivasankari Bhuvaneswaran

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