How Often Should I Test My Swimming Pool Water?

Prevention is always better than cure when it comes to algae and bacteria outbreaks in your pool. The only way to prevent this from happening is to check and maintain your chemical levels at the correct levels. How often should you test your pool water though?

You should test your pool water at least once a week during the summer. You can test your pool less often in winter, once every two weeks. You should also test your water immediately after bad weather as well as after it has been used by a large number of people, for example after a pool party.

There are many factors that affect how often you’ll need to test and treat your pool. It is also important for you to understand what these tests mean. Read on to find out why this is very important.

What Factors Affect How Often My Pool Should Be Tested?

Pools should be tested more often in summer months

In summer when your pool is being used often, you should test pool water at least two times a week. The increased water temperature allows germs and algae to grow faster.

You can ease off during the colder months when the pool is not being used

In colder weather when your pool is not in use, test it twice a month. When it is colder your pool will need less chlorine as it is more difficult for bacteria and algae to grow in these low temperatures.

When do you absolutely have to test your water?

In addition to the above, you should test your pool water immediately after bad weather such as rain or storms. You will also want to test your water if you have recently had a large gathering at the pool. Sweat and pee can really mess with the pool’s chemical balances.

What Exactly Are We Testing And Why?

Chlorine – Sanitises your water

Most pool owners will tell you that this is the most important chemical to keep an eye on because it sanitizes your pool and prevents it from going green. This is very important to the health and safety of your swimmers.

How to test the chlorine levels? The easiest way to check this is with chlorine test strips that you dip into the pool and compare the color change with the color scale provided.

  • Chlorine Test Strips – Very simple, these are plastic strips with a chemical pad on the end that change color when dipped into the pool water for a certain length of time. This color is compared to the color chart on the container to determine the chlorine levels in ppm.
  • Chlorine Test Kits – These come in many different configurations, but they all use the process of titration. You will take a water sample and follow the instructions by adding the directed amount of chemical (reagent) to the sample. You determine the level of chlorine by comparing the color of the water sample to the color chart provided. The exact details and process’s vary, so be sure to follow the directions provided with the test kit closely.
  • Electronic Chlorine Tester – As with all electronic testers, the arent always accurate, need to be calibrated and batteries changed. I would avoid these in general.
  • Automatic Chlorinator and Tester – These are quite fancy, they constantly test the water and add chlorine on the fly, automating the whole process. I would not use this as an excuse to skip testing manually and would only really recommend them for commercial swimming pools as they are very expensive and still need oversight and adjustment.

How often should the chlorine levels be tested? You should test this at least once a week and your ideal chlorine levels should be between 1.0 and 3.0 ppm

Total Alkalinity – Prevents corrosion and burning eyes

This should be tested before you test the pH levels of your pool. Correctly balanced alkalinity helps to stabilize your pool’s pH levels, giving you more accurate results when you test the pH.

If the total alkalinity is too low, the water can become corrosive to metals, staining the pool walls as well as irritated skin and eyes. If the total alkalinity is too high, the water will become cloudy and you will notice it is producing and depositing scale on surfaces.

How to test total alkalinity?

  • Total Alkalinity Test Strips – You simply dip these into the water and compare them to the color chart provided. My favorite way, and also the quickest and easier. Many of these strips also test for pH at the same time, really saving you a lot of time.
  • Total Alkalinity Test Kit – This is a test kit where you gather a water sample into a tube and add two re-agents, then another after. Just make sure you follow the instructions with the kit to the tee. It takes a bit longer but is more accurate.
  • Electronic Total Alkalinity Testers – These ones specifically can by burdensome to use. You will need to change the batteries and in addition, you have to use it in conjunction with re-agent solutions, like the test kits. I recommend the test strips or the test kit over this method.

How often should you test your chlorine levels? You should test this once a week and after every rainfall. You should also test after every time your pool is used by a large number of people. Your ideal chlorine levels are between 80 to 120 ppm.

PH Levels – Allows chlorine to do its job

Your PH levels work in conjunction with your chlorine levels. If you maintain your chlorine levels correctly, your PH levels will also be just right.

How to test the pH levels of your pool water. You are basically testing how acidic or alkaline your pool water is.

  • pH Test Strips – This is by far the easiest and my favorite way to test the pH. They are easy to use and are usually very cheap. You simply follow the instruction on the container, dip the strip into the water for the required amount of time, then compart it to the color chart to determine your pH levels.
  • Electronic pH Testers – These work well, but they can be problematic. You will have to change the batteries from time to time and they will also need to be calibrated which can become a bit complicated.
  • pH Test Kits – This is the most accurate way of testing the pH levels of your pool, but it takes a lot more time and effort than the previous two methods. It involves taking a sample of water in the test tubes provided and then dropping a solution into each tube. The color that the water changes will give you the pH level when it is compared to a chart. (Similar to the test strips)

How often should you test the pH? You should test this once a week and your ideal levels are between 7.2 to 7.8

Calcium Hardness – Avoid cloudy grey water

Calcium occurs naturally in your pool water and the calcium hardness doesn’t change in a short period of time, so it is acceptable to test this about once a month. You do need to test it even when your pool appears sparkling clean. Low levels will start to corrode the surface of your pool without you even knowing about it.

High levels are considered “Hard” and low levels are considered “Soft”

How to test the calcium hardness of your pool water?

  • Calcium Hardness Test Strips – Again, the test strips are by far the easiest and quickest method. Granted it is not as accurate as the test kits, but it will get you close enough to know if you’re within the range or not.
  • Calcium Hardness Test Kits – This is the most accurate way to test the calcium hardness of your pool water. They are usually inexpensive, but take a bit longer and require a tad more work.

How often should you test the calcium hardness of your pool water? You should test this about once a month and your ideal levels are between 200 and 400 ppm.


It is important to know what condition your pool water is in. Just because your pool water is clear, doesn’t mean that your water is well balanced. Out of balance water can be unhygienic to swim in. Out of balance water can also cause irritation on your skin and eyes.

Out of balance water can also corrode the surface of your pool and components as well as look unsightly, even green or cloudy.

For this reason, you need to test your water on a regular basis. This can be once a week during summer months, or as little as twice a month in the colder seasons.

There are many methods of testing all the levels of your pool water, from test strips which are the easiest and quickest but do not generally give the most accurate results. These are usually close enough to make sure your levels are within a range.

Electronic testers can be more od a pain than a convenience. They need their batteries changed and also need to be kept calibrated. Some of them even need to be used in conjunction with chemicals, which in my opinion, beats the object.

pH test kits are available when you are looking for accurate results, but it is more effort and time-consuming.

There you have it, I hope this article has helped you answer any questions about testing your pool water. If not, feel free to leave me a question in the comments section below.

PS. What does Dolly Parton put in her swimming pool? Chlorine chlorine chlorine chlorineeeee

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