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Accurate Pool Water Testing

Accurate pool water testing is the foundation of maintaining a safe, hygienic, fun, and pleasant swimming environment. A swimming pool with clear sparkling water is appealing and inviting. It tempts you to jump in with your clothes on. However, having a pool with sparkling clear water takes a lot of effort and hard work. Pool water testing is one of the pillars of clean and safe swimming pools.

As a pool owner, you must ensure a safe and comfortable balance of chemicals and pH levels. Your pool must stay free of harmful bacteria, algae, and other contaminants that could make it a health hazard. 

This article explores the significance of accurate pool water testing. I will examine various testing methods, monitoring essential parameters, and best practices to uphold water quality. 

Whether you’re a seasoned or a new pool owner, this article will equip you with the knowledge and tools to ensure a clean and safe swimming environment. 

The Importance Of Accurate Pool Water Testing

Every pool owner’s goal is to prevent recreational water illnesses (RWIs) and create a pleasant swimming experience. Poor maintenance often leads to low disinfectant levels that can permit the spread of germs that can cause diarrhea and skin and respiratory RWIs.

According to the Centers for Disease Control and Prevention (CDC), you should test your pool’s pH and disinfectant levels twice daily. The same source says you must test public pools at least hourly during peak time. As a backyard pool owner, you must test your pool two to three times weekly. 

Poorly maintained pool water can be a breeding ground for various health hazards compromising water quality. Unbalanced pH levels in water can cause skin rashes and itchy eyes. It can also damage your pool pipes and other equipment.

Unbalanced pool water can also lead to algae growth.

pool water testing

Types of Pool Water Testing Kits

When testing your pool water, the type of testing kit you choose depends on the size of your pool, the components to be tested, accuracy level, and affordability. 

Commonly used testing kits types are;

  • Test strips
  • Liquid reagents
  • Digital testers 

Let’s compare these different testing kits:

Test Strips

To test your water using test strips, dip the strip into your pool water and compare the strip’s color against a color chart provided with the kit. A standard test strip measures chlorine, free chlorine, pH balance, total alkalinity, and calcium hardness. Some test strips can also test for cyanuric acid (a stabilizer).

Test strips are affordable and suitable for backyard pools and pools that are not heavily used. However, test strips are single-use. Use a fresh strip every time you test your pool.

Collect saltwater pool water in a glass from the deep end of your pool for better results. Make sure to dip your hand to your elbow. Be careful when dipping that hand. I once fell into the pool trying to take a sample. Water on the surface may not give you an accurate reading because it’s exposed to many surface elements.

You must include a saltwater testing strip if you own a saltwater pool

Liquid Reagents

Liquid reagents are more accurate and produce more precise results than test strips. They test a more comprehensive range of water components than test strips.

Liquid reagent kits are slightly more complex to use than test strips. You must mix the provided chemicals carefully according to the instructions.

They are moderately more expensive than test strips but offer a good value for money, considering they are more accurate and perform a broader range of tests.

It is vital to observe suggested safety practices when handling chemicals.

Digital test kits

Digital test kits use electronic sensors to test different chemical elements in your pool water. They produce accurate, reliable, and consistent results. They can perform tests most reagents and test strips cannot, such as Total Dissolved Solids (TDS) and Salinity (Salt level). 

A single digital tester can test all the principal components you must check. You can test pH, free chlorine, salt, calcium hardness, and total alkalinity levels.

When using digital pool testers, dip the probe into the pool or a glass with a sample collected from the pool. You can read the results on the digital screen. 

Digital test kits are more expensive than test strips and liquid reagents. However, they are more accurate and straightforward to use.

Whatever testing method you use, follow the instructions supplied with the testing kits. Test strips are suitable for low-cost, basic water chemistry tests. However, if you want a more comprehensive test without breaking the bank, use liquid reagents. Digital testers suit pool owners willing to spend extra and need frequent and precise results. 

What To Test In Your Pool Water

As a pool owner, you should check the disinfectant (chlorine and bromine) and pH levels as recommended. Other water components you must also check regularly include total alkalinity (TA), calcium hardness, and salinity.


Chlorine is a yellow-green chemical element found as a gas at room temperature. It is the most commonly used disinfectant for swimming pool water.

As a pool disinfectant, chlorine is used as a compound such as calcium hypochlorite, a solid, or sodium hypochlorite, a liquid.

When calcium hypochlorite compound is added to water, chlorine reacts with water to form various chemicals, most notably hypochlorous acid (free chlorine). 

Free chlorine eliminates pathogens and bacteria by targeting the lipids in the walls of the cell walls and destroying the enzymes and structures inside.

It is vital to keep your pool chlorine levels within the recommended levels. The free chlorine level in your pool should be 2–4 parts per million (ppm)

Another chemical that you can use as a disinfectant in your pool is bromine. It is a volatile red-brown oily liquid at room temperature. It is easily identifiable by its pungent smell. Bromine levels in your pool should be 3-8 ppm.


pH measures the acidity and alkalinity levels of your pool water. The pH scale is from 0-14. A reading of 7 indicates that your water is neutral. Less than seven is acidic, and values greater than 7 indicate alkalinity.

The recommended levels for your pool are between 7.2–7.8. Higher pH levels above 8 reduce the ability of free chlorine to kill germs. 

Lower pH levels below 7 increase the effectiveness of free chlorine, but that comes at a cost. Higher acidic levels in your pool are corrosive and will damage your pipes. Acidic water also causes skin and eye irritations in swimmers.

Total Alkalinity (TA)

Total alkalinity measures the ability of water to offset acids in your pool water. It is measured by determining the amount of acid needed to bring a collected sample to a pH of 4.2. All the alkaline compounds in the sample are “exhausted” at this pH.

Testing your pool’s alkalinity levels is vital. It shows the ability of your pool water to neutralize acid from contaminants such as rain and urine.

Calcium Hardness

Calcium hardness measures how hard or soft your pool water is. The primary difference between hard and soft water is the mineral content. Hard water contains more minerals than soft water.

Approximately 85% of the US water supply is complex, according to the US Geological Survey (USGS). Your pool’s recommended calcium hardness levels are between 200— 400 ppm.


If you own a saltwater pool, you must check the salt levels. Pool salt levels should be maintained between 3200 — 3600 ppm. Low salt levels will reduce the capacity of the salt chlorinator to produce chlorine. If your pool has low disinfectant levels (chlorine), it creates suitable conditions for algae growth.

Testing Techniques

The quality of results you get depends partly on your testing technique. Always follow the manufacturer’s instructions for best results. Follow these basic practices for accurate results:

  • Read the manufacturer’s instructions.
  • Gather all your testing equipment before you start.
  • Clean sample equipment.
  • For consistency, test at the same place and time.
  • Dip or collect water samples as per the manufacturer’s manual.
  • Follow wait times (where applicable).
  • Read and record results carefully.
  • Clean and store your testing equipment and place it in a safe, lockable room.

Depending on the results, take corrective action if any tested parameter values are outside the recommended levels.

Frequency of Testing

The CDC recommends that public pools be tested at least twice daily or hourly if in heavy use. The same organization suggests that backyard pools should be tested at least two to three times weekly.

Regularly testing your pool may be impossible due to poor weather conditions like rain and snow. A heavily used pool can also be difficult to test at the recommended intervals. In such cases, test your pool at the earliest possible opportunity.

Interpreting Test Results

After testing and recording your pool water results, check to see if they are within the safe levels for your pool. Take immediate corrective action if any tested parameters are outside the recommended range.

Here are the recommended levels:

ParameteOptimal LevelsPossible Remedy
pH7.2-7.8If the pH is too high (above 8), add a pH reducer (muriatic acid).
If the pH is too low (less than 7), add a pH increaser  (sodium carbonate or soda ash).
Total alkalinity (TA)Between 80—120 parts per million (ppm)To raise TA, add sodium bicarbonate (baking soda).
To lower TA, add acid. You must be careful because acid affects pH levels.
Free chlorineBetween 2—4 ppmTo increase free chlorine, add Chlorine liquid, tablets, or granules.
If too high, let it reduce naturally or use a chlorine neutralizer.
Combined chlorine (chloramines)As close to zero as possibleAdd a high dose of chlorine to shock the pool.
Cyanuric acid (CYA)  (Stabilizer)Between 30—50 ppm (outside pools using chlorine)To reduce high CYA levels, dilute with fresh water.
Calcium hardnessBetween 200—400 ppmTo raise calcium hardness, use calcium chloride.
To lower calcium hardness, use a pool water softener or dilute pool water with fresh water.

Risks Posed By Unbalanced Pool Water

Below are some of the risks related to unbalanced pool water: 

Algae Growth

Algae are microscopic organisms that can multiply rapidly in your pool if conditions are favorable. 

Improper levels of pH and chlorine create an environment conducive to algae growth. Algae turn your pool water green or cloudy, leading to unsightly and slippery surfaces on your pool walls and floors. 

Bacteria Habitat

Poor pool water quality creates conditions favorable for bacteria growth and multiplication. 

Bacteria like E. coli, Legionella, and germs such as Giardia, Cryptosporidium, and Hepatitis A can rapidly infest your pool.

You can contract skin, ear, or eye infections, causing irritation, rashes, or red eyes after swimming in a bacteria-infested pool. 

In more severe cases, exposure to certain bacteria may lead to gastrointestinal illnesses, respiratory problems, or Legionnaires’ disease, a severe form of pneumonia.

Skin And Respiratory Irritations

Chloramines, which result from the reaction between chlorine and contaminants like sweat or urine, can also cause respiratory issues, especially in indoor pools. 

When exposed to unbalanced pool water, swimmers may experience symptoms like coughing, wheezing, or shortness of breath.

Water with high pH levels or low sanitizer levels can cause eye irritation and discomfort for your swimming pool users. Red, itchy, or stinging eyes are common complaints in pools with water chemistry issues. 

Common Pool Water Testing Problems

Pool water testing can be challenging for new and seasoned pool owners. As a pool owner, you might encounter difficulties testing your pool water for various reasons. 

Here are common pool water testing problems and how to overcome them:

Inaccurate Reading

  • It can result from faulty equipment or poor sample collection and contamination of testing equipment.
  • Check that your equipment is functioning correctly before testing. 
  • Follow the recommended sample collection method.

pH Drift

  • pH levels may fluctuate due to heavy rain or heavy pool usage— 
  • test your pool pH levels and adjust as needed.

High Chlorine Demand 

  • High chlorine demand can result from heavy pool usage, high temperatures, or contaminants in your pool. 
  • Shock the pool with a higher dose of chlorine.

Test Results Outside The Ideal Range

  • Testing results outside recommended range can be caused by poor handling of equipment, insufficient water testing, or poor chemical maintenance. 
  • Double-check your equipment and how you use it. 
  • Improve water circulation in your pool by adjusting your pump and filter settings. 
  • Keep accurate records of pool chemical maintenance activities

Pool Maintenance Tips 

Many factors influence pool water quality. Some factors, such as weather, are beyond the pool owner’s control. However, you can manage most conditions with good pool maintenance practices.

Here are pool maintenance tips:

  • Clean your pool water filter regularly
  • Always remove surface contaminants 
  • Use a pool brush to scrub the walls, floor, and steps to prevent algae and other build-ups.
  • Shock your pool regularly
  • Keep a steady pool water level
  • Cover the pool when not used.
  • Periodically drain and refill your pool.


Accurate pool water testing is vital for maintaining a safe, healthy, clean, and pleasant swimming environment. As a pool owner, you are responsible for regularly testing and maintaining the recommended levels of crucial water elements. 

Alkalinity, pH, salinity, and calcium hardness levels should be kept at optimal levels recommended by the CDC or the local regulatory bodies.

Choose a suitable testing kit to obtain the best pool water test results. Test strips are easy to use and inexpensive, but results are subject to the user’s interpretation. 

Digital test kits and liquid reagents can test for broader parameters. However, the costs of acquiring these kits are prohibitive. When using test kits, always follow the manufacturer’s instructions. Keep your testing equipment clean and safe after use.

Accurate pool water testing enables you to make informed decisions about your pool water quality. It helps you take appropriate corrective measures to maintain a clean and safe pool.


  • Raoul Hayes

    Raoul Lobo is a seasoned expert in the realm of home appliances and environmental comfort. As a prominent author at, Raoul's passion and expertise shine through in his insightful articles and guides. With years of hands-on experience, he has become a trusted source for readers seeking advice on pools, washers, dryers, and a wide range of other appliances.

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