How-To: Use Test Strips

Hot Tub and Swim Spa test strips can come in all manner of varieties, testing up to seven various parameters of your spas water chemistry. Read on for the Hydropool North West Test Strip Guide.

We hope to demystify the basics of test strips, and help you get to grips using them with your new spa.


Getting into hot tub water chemistry can be a daunting task, with so many different chemicals and tests available, but to start we’d recommend concentrating on the 3 main chemicals:

  • Sanitiser (Chlorine or Bromine)

  • pH

  • Total Alkalinity

You’ll want to make sure that your test strips specify that they’re intended for hot tubs or spas. There are many similar water testing products designed to test anything from pools to ponds. As long as your strips have these three chemical tests, you’re good to go.

Additionally, you’ll need to know which sanitiser you’re using in your spa, and buy the relevant test strips. Most test strips will state on the front of the packaging that they’re either for chlorine users, bromine users, or both!


Before starting, make sure your test strips are still in date, clean, and dry.

When removing a test strip from the container do not touch the test squares, and make sure your hands are dry; prematurely getting water on your strip or inside the bottle will ruin your test strips and give inaccurate results when used.

Each individual square on the strip tests for something different, and corresponds to the colour charts on the back of the packaging. The test reads from top to bottom, and the result reads across the colour gradient.

Basic 4-Way test strips, designed for both Chlorine and Bromine users. Includes Bromine, Free Chlorine, pH & Total Alkalinity tests.

Each step of a test has a value; for example Total Bromine is measured in ppm (parts per million), and the range is 0-10.

An “OK” indicator shows the range at which your hot tub should measure, in this case Bromine should be between 2-4 ppm.

These numbers will help when looking at your chemicals. For example, bromine granules will tell you how much you need to add to raise your Total Bromine levels by 1, 3, or 5 ppm.

(If you can’t tell which way up your strip or chart should be, all will become clear once you’ve dipped your first test and the colours become apparent.)


The following instructions are typical use of a water test. However, they can vary depending on brand, please make sure you read the instructions to ensure accurate results.

  • Open your hot tub up.

  • With dry hands remove one test.

  • Fully submerge your test into your spa water.

  • Swirl the test for two seconds.

  • Remove the test: Do not shake off any water.

  • Hold flat and level for 15 seconds.

  • Compare to colour chart.

You will notice the test results develop over the 15 seconds. Reading the results at this point is crucial, as any earlier or later will result in an inaccurate test.


So, the results are in and now you need to get stuck in with water care. You can find some information on our blog post Water Chemistry: Where To Start?

Once you’ve used up your current test strips you may want to branch out and start testing for water hardness or any number of parameters to ensure the best care for your hot tub or swim spa. You may even want to take your testing a little further and invest in a digital testing kit.

There are all kinds of water tests to be done, but as long as you’re testing and treating the main three listed above, you’ll have a happy healthy hot tub.