How to Test Pool Water Accurately

It’s important to learn how to test pool water, and do it at least once a week to make sure the pH and alkalinity are balanced, and to keep your sanitizer level in check (i.e. chlorine at 3 ppm).

What most pool owners don’t know, however, is there’s a right and wrong way to test your water, no matter what type of testing you’re doing. It all starts with the water sample.

The Water Sample

To take a proper water sample, use a clean cup or bottle (with cap if you’re taking it to the pool store) and hold it upside down so that the opening is facing the floor. Insert into the water elbow-deep and turn it right side up to collect the sample. Do not take the sample near any return jets or skimmer opening. If possible, take the sample from the absolute middle of your pool.

Now you can take this sample to your pool store or check it yourself.

Using Test Strips

For home testing, this is my personal favourite. It’s easy to do and very accurate – much more accurate than using a liquid test kit because of human error when it comes to matching up the colours and using chemical droplets.

Take your water sample and quickly drip one, dry strip into the water. Hold it still in the air for about 15 seconds (do not shake off the excess water). Then match up the colours of the strip to the back of the bottle to get your readings.

There are all different kinds of test strips you can buy that check for all sorts of things, but you really only need to check for pH, alkalinity and free chlorine.

Use test strips at least once a week. I like to check my water every other day. And bring a sample to your local pool store once a month to have it professionally checked – also when opening and closing your pool.

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Using a Liquid Test Kit

There are very advanced liquid test kits, but for home use, just stick with pH and chlorine or phenol red and OTO. Phenol red is a red chemical you add to a small sample of water to check the pH. The redder the water, the higher the pH.

OTO is the chemical that tests for total chlorine. It’s a yellow liquid you add to your sample. The more yellow, the more chlorine.

With a liquid test kit, it’s hard to see the low end of the colors. Make sure you use a white background to examine the colors to be accurate.

For more in-depth guidance on how to use liquid and reagent pool test kits, check out our post on How to Correctly Use Pool Test Kits.

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Conclusion

Pool water testing is very important if you want to keep your pool crystal clear. In fact, pool testing can save you a lot of money in the long run by making sure that you catch pool chemical imbalance early on and will allow you to correct these chemical levels before they become a real headache.

For more information on pool chemical testing, check out our Ultimate Guide to Testing Your Pool Water. 

Sound like a lot of work? Check out our Wireless Sensor Technology blog post to learn more about wireless pool sensors and how they can make manual pool testing a thing of the past!

Post author:

Tom Hintze

Head of eCommerce & Operations at Mr Pool Man,
Co-Founder at Water TechniX

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