How Often Should You Test Your Pool Water? 

The weekend is over, and so is the massive pool party you threw for your friends and family. Just think of all the undesirable substances that have entered your pool water, including red SOLO cups. Pool water testing is the best route to a healthy and easy-to-maintain system for all pool activities. But how often should you test your pool water? Is it a daily, time-consuming task? 

Testing your pool water is not as technical as it sounds. You just need to buy the right testing materials and know what you’re testing for. It helps you determine the presence of unwanted substances, as well as how much and what chemicals to put into the water to maintain a safe swimming experience. If you’re a beginner at testing water levels, we suggest testing the water every 2 or 3 days until you learn how levels fluctuate. 

If you’re not sure what to test for, we’ve got you covered. We will go through the ideal ranges of every chemical component you should test for, the frequency of testing, and methods to adjust different chemical levels. 

How Often Should You Test Your Pool Water?

There is no one straightforward answer to this question. Truth of the matter is, it depends on a lot of factors. Each swimming pool is made up of different materials, and constructed in different shapes and sizes. Some pool water tests are required on a weekly basis, others can be performed once a month. 

Special circumstances may increase the need to perform water tests, such as a storm that has recently hit your area. Here are some other factors that determine the regularity of pool water testing:

• Heavy storm (excessive rainfall)
• After a big pool party or heavy usage
• If your pool has had an algae infestation
• When you close your pool for the winter
• When you open your pool in the spring. May be good to have pros check chemical levels and make recommendations
• Any time you have pool issues or are uncertain about chemical levels

The following section will cover the components in your pool water that require testing, and their ideal levels for a healthy and balanced pool water. We’ll cover methods on how to test each level in a different section. 

Primary Components

For as long as you own a swimming pool, testing the following levels is a maintenance task you’ll never get rid of. 

pH Level

This test measures how basic or acidic your pool water is, on a scale of 0 to 14. Anything above 7.0 is considered basic, and anything below 7.0 is acidic. The ideal range for your pool water is from 7.4 to 7.6. 

Keeping the pool water pH within this range helps the chlorine work effectively. If not, your pool water will not be sanitized. Water that’s too basic or acidic can damage the pool system and cause irritation to your skin and eyes.  

• To increase pH: You can add borax (sodium borate) or soda ash (sodium carbonate). Borax won’t increase alkalinity levels, which could make it the better option. 
• To decrease pH: Muriatic acid or sodium bisulfate will do the trick. These chemicals also lower alkalinity, so you can add baking soda to raise alkalinity back to a desired level. 

We recommend testing your pool water’s pH level once a week during regular use and mild temperatures. You should test it more often after heavy use, exceptionally warm temperatures, or rainstorms. If you’re a beginner at testing water levels, we suggest testing the pH every 2 days until you learn how these levels fluctuate. 

Alkalinity Level

Alkalinity has one major role: protect your pool water’s pH level. Swimmers, pool toys, debris, and rainwater can potentially disrupt the water’s pH. Alkalinity helps prevent disruption and acts as a buffer to minimize fluctuations in pH levels. The ideal alkalinity range for your pool water is between 80 and 120 ppm (parts per million). 

• To lower alkalinity without lowering pH: First, lower both with muriatic acid or sodium bisulfate and then raise the pH back to desired levels by aerating the pool or adding sodium carbonate.
• To raise alkalinity without raising pH: You can add sodium bicarbonate (it will only slightly increase the pH). 

Similar to the water’s pH, you should test the total alkalinity level once a week. However, you should test it 2 to 3 times a week during peak swimming seasons or if you’re a beginner who needs to learn about fluctuating levels. 

Cyanuric Acid

Also known as CYA, cyanuric acid protects your pool water chlorine from the sun. It allows the water molecules to hold onto free chlorine. If the CYA levels are too high or low, chlorine won’t be effective in sanitizing the pool water. On the bright side, CYA will not affect the pool’s pH, alkalinity, or calcium hardness levels. 

• To lower the CYA level: Diluting the water is the only way to reduce the CYA level. Drain some of the water in your pool and replace it with filtered water.
• To raise the CYA level: This one’s quite straightforward, just add more CYA! 

The ideal range of CYA for your pool water is from 30 to 50 ppm. Wanna hear something great? You’ll only need to check the CYA level once a year! This is generally when you open your pool. 

Free Chlorine Level

Chlorine is the most common sanitizer for your pool water. You can use different forms of chlorines, including granules and tablets. Free chlorine is the amount of chlorine that sanitizes your pool water. The ideal level is between 1 and 3 ppm. Adding chlorine to the pool water will increase the amount of free chlorine. 

It is important to keep the level of combined chlorine lower than free chlorine levels. Combined chlorine is free chlorine with contaminants. You should also add chlorine after you adjust the pH level in your pool water. 

It is important to go through the two different chlorine types: stabilized and unstabilized. Stabilized chlorine contains CYA, while unstabilized chlorine does not contain any CYA. The type you choose depends on the current CYA level in your pool water. 

As for the testing frequency, there is no change from pH and alkalinity levels. You should test for free chlorine levels 2 to 3 times a week till you learn how to maintain your pool water chemistry, or after a period of heavy use. Once you’ve learned how to manage fluctuations, you can check the free chlorine levels once a week during regular pool use. 

Secondary Components

A lot of pool owners may focus on pH or alkalinity levels, but there are more components in the pool water to keep an eye on. These secondary components include total dissolved solids, copper, and phosphate. 

Phosphate

It can enter your pool from lawn fertilizers or other similar sources. Algae feed on phosphates, so you’ll know you have a phosphate problem when algae turns your water green. You can purchase a phosphate test kit to check on the level once a week.

If levels are higher than normal, you can apply phosphate remover to control or reduce phosphate levels. If it’s too late and you’re already dealing with green water, then you’ll need to apply algaecide instead. 

Combined chlorine 

You don’t want contaminants with your free chlorine. Combined chlorine may lead to: 

• Dry or irritated skin
• Burning red eyes
• Respiratory problems such as asthma and a persistent cough

To test the level of combined chlorine in your pool water, you can purchase a DPD (N,N-diethyl-p-phenylenediamine) test kit. We recommend checking combined chlorine levels at least once a week, depending on pool usage. If the levels are too high, you can superchlorinate the water or apply non-chlorine shock. 

Note: Superchlorination process is when you temporarily increase free chlorine levels to sanitize your pool water. 

Metals 

Ever wonder what causes those stains on your pool surface? Metals such as copper and iron may cause that uninviting pool look. You can purchase test strips specialized for each type of metal. You should test for metals whenever you notice signs that your pool water is contaminated, including stains and rust. 

Total dissolved solids 

TDS is a measurement of everything that has dissolved in your pool water, including dust and swimmer waste. High TDS levels suppress the activity of free chlorine and may cause corrosion to your pool equipment. 

You should test your pool water with a digital test meter like SafeDip if you’re having repeated issues with maintaining chlorine levels. The only way to lower high TDS levels is water dilution, similar to lowering CYA. You’ll need to replace the current pool water with fresh, unsaturated water. 

How to Test Pool Water

Metals and phosphate require specialized pool test kits, but testing the levels of primary components is not as complex. There are four ways to maintain your pool water chemistry, ranging from test strips to collecting a water sample for professional analysis. Some methods are quicker or costlier, so we’ll let you decide which way to go. 

Pool Test Strips

Test strips are super quick and easy to use. They’re typically less expensive than liquid test kits, but you’ll go through them quickly. Test strips generally test for pH, alkalinity, free available chlorine and total chlorine levels. You can purchase them at pool stores or online retailers like Amazon. 

Here’s how to use pool test strips:

• Dip a strip into the water without letting it soak for long (2 to 3 seconds). Submerge the strip at least 12 to 18 inches below the water surface. Move away from any jets or skimmers. 
• Hold it still in the air for approximately 15 seconds. Don’t shake it around! 
• Compare the test strip to the guide on the container and match up the colors on both. 
• After viewing the result, adjust your pool chemicals accordingly

Pro Tip: Test strip containers may provide general guidelines on balancing water chemical levels. 

Liquid Test Kits

Liquid test kits cost higher and are more accurate than test strips. They include reagents like phenol red and orthotolidine to test pH and chlorine respectively. Liquid kits are good to have as part of regular maintenance testing. Here’s how to properly use liquid test kits:

• Collect a water sample. The collector is provided in the test kit.
• To test the water pH level, add the right amount of drops of phenol red to the collected water.
• On the side designated for chlorine testing, add the required number of OTO drops to the collected water.
• Place the caps back on each tube to seal them. Gently shake the reagents with the water to fully combine the different liquids. 
• Hold the collector up to a white background (sheet of printing paper) and compare the colors of the collected water to the collector’s color scales.
• Strong red water indicates that the pH level is high. High chlorine levels will make the water yellower.

Note: If pH and chlorine levels are low, water colors will be fainter and difficult to see. 

Digital Pool Testers

Digital pool testers get you quick and accurate readings. They are extremely easy to use, often featuring an LCD display and water-resistant housing. Some testers also come with a digital memory function to view results history. You won’t need to worry about matching colors like other manual tests, which could be useful for pool owners with color blindness. 

Most digital testers have electrodes that measure chemical levels in the water itself, followed by an accurate measure. For the high-tec option, you can install digital testers in the pool that connect an app on your smartphone. You’ll get all the data on your pool water chemistry at the touch of your finger!

One major downside is that they’re more costly than pool strips and liquid tests. However, it’s a worthy investment that provides a reliable, complete, and fast water testing solution. 

Provide a Water Sample to Pros

If you collect a sample of your pool water, pool experts will test your water through a computer testing system and provide recommendations on precisely what your pool needs. Here’s what you can do:

• Use a clean, rinsed out water test bottle.
• Collect a water sample somewhere in between the skimmer and return jets for optimal reading.
• Dip the bottle at least 12 inches deep into the water to collect the sample (elbow deep).
• Cover the bottle and bring the fresh sample to your local pool pro. Don’t let it sit in your car for too long!

The pros will then perform a computerized digital test that even measures secondary components such as TDS. 

Note: Make sure the pump has been circulating the pool water for at least one hour before collecting the sample. 

Salinity Levels for Saltwater Pools

You should check the salinity level of your saltwater pool once a month. Ideally, the salt levels should range from 2,700 to 3,400 ppm. If you’re a new pool owner, you can test the levels weekly just to be sure. 

Some salt chlorine generators have digital screens and Tri-sensors to tell you when and how much salt to add to your pool. You can also purchase saltwater test strips for quick and easy results. 

How Add Pool Chemicals Safely

So you’ve tested your pool water and realized you need to apply some chemicals to balance it out. You may be worried of mishandling the pool chemical or spilling the harmful products near your garden bed. No need to worry, we’ll provide you with tips on how to apply the chemicals safety to your pool water. 

• Always follow the chemical’s instructions to ensure safe use.
• Wear protective equipment and clothing such as gloves and safety glasses. 
• Use separate, clean plastic or metal measuring cups to transfer chemicals. Wood scoops are not recommended.
• Handle the chemicals in a ventilated area.
• Do not mix different chemicals together.
• Do not smoke or consume a beverage while handling pool chemicals.
• Don’t put spilled chemicals back into their container.
• Don’t expose the pool chemicals to heat or flames.

FAQ About Pool Water Testing

More Clean and Less Green Pool Water

We hope you were a front-row student in chemistry class who did every homework. Just kidding, you won’t be dealing with any complex formulas!

Pool water testing is an essential and understated part of pool maintenance. As seen with test strips or digital testers, it is not a back-breaking or time-consuming task. If certain levels are not in the ideal range, you may need to apply chemicals to keep the pool water clear and sanitized. 

Maintaining proper pH and alkalinity levels is pool chemistry 101, but they’re not the only components you should check on. Calcium hardness, phosphate, and copper levels should be tested weekly or monthly, depending on pool usage and other factors we’ve covered. 

But if you’re not confident of testing your pool water, or unaware of which chemicals to apply, hire a local pool professional who can handle the pool testing and pool cleaning for you.

Main Photo Credit: Isai Hernandez / Canva Pro / License