Pool Water Testing 101 (Complete Guide How to Test Pool Water)

The correct measuring method and the precise determination of the parameters in the pool water is essential to identify disturbances in the water balance and to eliminate them with suitable means. But how is the pool water tested correctly, and how often should this occur?

The water levels in the pool can be determined with calorimetric, titrimetric, photometric, or electrometric water testers. For beginners, the calorimetric pool water testing method is often sufficient to test the pool water, but measurement errors are always to be expected.

In this article, you will learn all the common measuring methods for determining the concentration of parameters in your pool, how you can most easily test the pool water, and how to prevent an imbalance in your pool.

Important parameters in pool water

Here you will find a helpful overview of the most important basic parameters in the pool and whirlpool.

I’ve also included notes on when and how often you need to test the pool water.

Parameter Level Water Test
Chlorine 0,3 – 1,5 ppm Daily
Bromine 3,0 – 5,0 ppm Daily
Hydrogen Peroxide 3,0 – 8,0 ppm After application
pH Value 7,2 – 7,6 Daily
Alkalinity 80 – 120 ppm 1x/Month
Calcium 200 – 400 ppm 1x/Month
Cyanuric Acid 30 – 50 ppm 1x/Month

Stick to these pool parameters, and you will have crystal clear water in the swimming pool in the long term.

Above all, it is important that the pH level and the alkalinity are correct and that a good disinfectant such as free chlorine is available in the water.

In the next chapter, you will find out which methods you can test the pool water at home.

Suitable measuring methods for pool water testing

The individual concentration of the parameters in the pool water can be tested with different measurement methods.

Pool owners can choose between the following methods to test the pool water:

  • Colorimetric: The pool water is measured with test strips or with the help of an indicator (liquid or in the form of tablets) in cuvettes. The color scale shows you the result.
  • Titrimetric: First, some water is prepared as a reaction liquid, then a liquid agent is used. The result is determined by the number of drops used.
  • Photometric: For the photometric water test, a measuring device is required that examines a water sample. The measuring device then determines the differences in concentration and indicates the values ​​- with this method, almost every parameter in the swimming pool can be measured.
  • Electrometric: An accurate measuring instrument is an electrometric measuring device that works with probes. It is easy to use, and the test results are reliable, but the devices are expensive.

In practice, the results of the individual measurement methods differ significantly.

This is not unimportant, since an incorrect measurement result leads to increased use of chemicals and extra costs for pool cleaning – you can read about the exact consequences of wrong pool water testing methods at the end of the article.

You can expect valuable results only with the proper measuring method when testing the pool water.

But which water tester is the best for beginners in private swimming pools?

The exact differences between the water testers and how you should use them to test the pool water can be found in the following subsections.

Tip: You should know that the concentrations in the swimming pool are measured in ppm (parts per million) and that this corresponds to 1 ppm = 1 mg/l. Don’t get confused because one water tester shows the color scale in ppm and the other in mg/l.

Inexpensive test strips for quick tests in the pool

Test strips are one of the most common ways to test pool water.

The test strips are relatively cheap compared to other measurement methods and are sufficient for beginners with a small pool.

But how exactly are the test strips used in the pool and then evaluated?

Individual scales on the test strip have different concentrations of a particular chemical. If a strip is held in the water, the color changes, and the test strip can be evaluated using the color scale provided (usually on the packaging).

You can use the test strip to determine the most common parameters such as pH level, alkalinity, or chlorine level – it always depends on which test strips you buy.

However, when using test strips, an incorrect pH level and alkalinity result must always be expected since the evaluation of the test strips is not one of the most accurate.

This is important because incorrect results overload the pool with disinfectants or cloudiness. After all, the parameters cannot be coordinated with one another.

Furthermore, the measurement results of the pH level can differ depending on the manufacturer – it is best to avoid cheap products from unknown suppliers.

Many still forget that the evaluation with the test strips is limited. The pH level on the color scale of test strips usually only goes up to 8.4.

This is often not enough when testing the pool water, as the pH level in your pool can go up to 14. How should one then make an exact dosage of the pH minus?

The only thing that helps here is to try it out and carefully approach the chemistry.

Tip: The test strips are sufficient for simple control of private swimming pools. However, if the pool is cloudy or has other problems, you should use other measuring methods.

Pool water testing with a liquid test kit for more precision

Liquid water testers belong to the calorimetric measuring process and are more precise than the test strips.

With liquid test kits, in addition to the pH level and free chlorine, even bacteria in pool water can be measured. But that always depends on which liquid test kit you are using.

It is easy to use: The supplied cuvettes scoop up some pool water and add the liquid indicator.

The water reacts with the indicator and changes color. Then the discolored water is compared with the supplied scale – usually, the scale is printed directly on the cuvette – and the water level in the pool is determined in this way.

It is important that you drain the cuvette in front of a white wall in the shade to avoid incorrect evaluations. Alternatively, you can hold the often supplied white card behind it or use a simple white sheet.

Test your pool water with tablets in cuvettes

The water tests with the Rapid test tablets work the same as the liquid water testers, only that a tablet is used instead of drops.

After taking some of the pool water into the small container with the color scale, one of the test tablets is inserted. The container must then be covered and shaken so that the indicator dissolves and the watercolors.

For the evaluation, the discolored water is compared with the printed color scale.

As always, the following applies: Read the manufacturer’s instructions and pay close attention to them.

With this measuring method, important parameters such as the pH level, the active oxygen, or the chlorine in the pool can be determined – this measuring method is usually sufficient for laypersons.

It is also practical that the Rapid test tablets are available separately from specialist retailers, and costs can be saved.

Such tablets are not only used in cuvettes as indicators to determine the water level. In combination with an electronic water tester, far more precise results are possible.

Electronic water tester for precise water levels ​​in the pool

An electronic water tester is – of all the measurement methods already mentioned – the best method for pool water testing.

The operation of digital pool testers is relatively easy after a short training period, and the measurement results are reliable. It can also be used to determine most of the water parameters ​​in the pool.

Normal test strips or liquid test kits cannot keep up with the e-measuring devices for determining the pH level.

Unfortunately, these devices are not cheap, but the time savings for troubleshooting the water treatment are immense.

This saves stress and reduces the use of pool chemicals.

I cannot speak of a measuring device test winner for the pool, but the device shown here would be an enrichment for pool maintenance for every pool owner.

If you are looking for a reliable water tester with which you can precisely test the pool water and meticulously dose the chemistry based on the values, then an electronic pool water tester is recommended.

Tip: Simple digital pH testers can only determine the pH level but cost almost half that of a universal measuring device. If you have frequent problems with the quality of the pool water, buying a multifunctional water tester would be worth considering.

Why is a regular pool water test important?

The pool water must be clean, and a regular water test in the pool is necessary.

Even slight deviations from the pH level lead to an imbalance in the water balance. The effects can be seen in the form of various problems with the pool water up to serious damage to the pool.

And why is it important to check the pool water regularly?

Maintain the water quality in the pool

For crystal clear pool water, compliance with certain limit levels ​​is crucial, and continuous water tests are necessary in order to be able to comply with them.

A deviation from the ideal parameter in the pool leads to clouding of the water quality, foam formation, stains on the foil, or a film/edge of grease.

Minimize health risks in the swimming pool

Compliance with the limit levels ​​when using disinfectants is not only important for the water quality, but also to minimize health risks in your swimming pool.

Exceeding the specified limit levels ​​for chlorine and other disinfectants can lead to allergic reactions and even cancer.

Prevent damage to the pool

Disregarding the ideal levels ​​for water treatment in the pool, in addition to clouding the water and the health risk, damage the pool and the expensive pool equipment.

Lime deposits on the walls and in the sand filter system, rust formation on ladders, torn-out joints, pool stains, and much more are just a few of the possible damage caused by a pH level that is too high or too low.

Avoid extra pool maintenance costs

The damage to the pool and equipment caused by neglecting the control of the pool water must be repaired. Of course, this all costs time and money.

Another cost factor that goes along with the irregular water tests is an incorrect measurement method.

Incorrect test results for the pH level lead to excessive use of pool chemicals and consequently to increased pool maintenance costs.

Hopefully, you can see why it is important to test the pool water regularly and, if necessary, to optimize it – with an electronic water tester, this is easy, and the results are reliable.

The advantages and cost savings that result from the ongoing control of the pH level and the optimization of the water in the pool, mainly the costs of a tried and tested water tester.

But how is the pool water properly tested in order to prevent incorrect measurement results for pH levels ​​etc., and how often should this take place? Read my tips above in the article.

How often should you test the pool water?

Like a freshly baked pool owner, pool maintenance seems complicated and time-consuming.

It starts with the question of how often the pool water has to be tested to keep the pool clean.

This is not an unimportant question when you consider that if the pH level deviates within a day or even in a few hours – the pool water can turn green. The consequences are additional cleaning work and additional costs for chemical pool cleaners.

The pool cleaning and the associated control of the water parameters ​​can be so easy.

As a basic rule, you can remember: The pool water is generally tested after every extensive pool cleaning and, if necessary, optimized through the use of pool chemicals.

Do not worry.

You don’t have to test all the parameters ​​in the pool after you’ve just scrubbed the pool.

All parameters serve a different purpose in the pool and fluctuate differently. Some water parameters, such as the pH level, need to be checked more frequently and others less often.

It is best to have a look at my table with the important basic parameters for the pool earlier in the text. For more details, read my ultimate guide on pool chemicals that I already linked to you at the beginning of the article.

Note that the specified frequency of measurement of the pool water can vary depending on external circumstances and must take place more frequently in summer.

Suppose the pH level is measured in the pool in the morning, and it rains heavily in the afternoon, whereby the acid rain lowers the pH level below 7.0.

In this case, do not wait long to measure the pH again and possibly increase it with a pH plus.

Furthermore, the bathing habits play a role, how strongly the individual parameters are influenced and how often the values ​​have to be measured so that the pool water remains clean – a half-daily measurement is then necessary for the pH level.

The water temperature and the use of stabilizers also have an influence on the various parameters and consequently on the water quality in the pool.

The control of certain parameters must then be increased accordingly – without exaggerating.

Further up in the text, you will find more information and a detailed explanation of the individual parameters.

Do you have any further questions about pool water testing?

Contact me at @contactswimfool on Twitter, Facebook, or Pinterest. I will help you personally.

Have fun testing pool water.

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Hi. I'm Max Berg. I've been in the pool industry since 2015 and have always felt drawn to water. I'm the author behind swimfool.com, where I share my years of experience in pool maintenance and give helpful tips on keeping a swimming pool or hot tub clean. My tips reduce the costs of water treatment and protect the environment.

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