Pool Chemicals 101: A New Pool Owner’s Guide to Healthy Pool Water

Summer is here and you can’t wait to go for a swim! However, as a new pool owner, you probably have a lot to learn about pool maintenance and pool water quality.

Water quality refers to pool water that is properly sanitized and free from organisms that can make swimmers sick. Maintaining good water quality is essential to safe swimming and an enjoyable swim season.

By itself, a swimming pool is just a large tub of water. Standing out in the open in the warm summer sun, the water can become home to invisible pool crashers like bacteria, protozoa and algae. These organisms can cause illness, infection and skin irritation in humans. If left unchecked, some contaminants also may damage your pool surface and equipment.

Pool water that is chemically balanced and disinfected is the safest water for swimming. Removing pool water contaminants helps reduce damage and wear to your pool equipment. Maintaining good water quality is a way to protect the significant investment you made when you installed your swimming pool by ensuring it stays in good shape.   

Test Strips - Pool test strips are small, chemically treated paper strips that you immerse in your swimming pool water. To test, find a spot away from the skimmer opening and return jets. Hold the strip between your fingers and dip your arm elbow-deep into your pool, or use a clean glass to collect a water sample. Wait about 15 seconds. Compare the sensor pads on the test strip with the color chart on the test strip container. If any of the levels are too high or low, take the proper steps to balance the water.

Test Kit - While a water test kit might seem more complicated to use than test strips, the results generally are considered to be more accurate. A typical water testing kit contains a water collection tube with a built-in color chart and bottles of liquid solution - one for each water quality indicator. Follow the test kit instructions to determine water quality and balance chemicals as needed.

Digital Tester - There are several types of digital testers on the market. While a digital pool water tester can be expensive, they are typically quite accurate and easy to use, according to Pool Care for Dummies. A digital pool tester analyzes your water quality and displays the results on a digital read-out.

If you don’t feel comfortable performing any of these testing methods, your nearest pool store should be able to test your water for you. Use a clean, empty water bottle to collect between 12 and 16 ounces of pool water and take the sealed bottle to your swimming pool dealer for results.

What is Chlorine?

Chlorine is one of the best ways to kill germs in your pool water and help keep diseases from spreading, according to the Centers for Disease Control (CDC). Pool chlorine also helps break down dirt and prevent algae growth.

Other options for pool sanitizing include bromine and PHMB, also known as biguanide. A saltwater swimming pool uses a generator that creates chlorine through a chemical reaction. The information below pertains only to chlorine additives.

Optimal Chlorine Levels

For optimum germ-killing efficiency, the level of chlorine in your pool should be between 1 and 3 parts per million (1 ppm-3 ppm).

Why Should You Balance Your Chlorine Levels?

Maintaining ideal chlorine levels in your pool ensures that the water continues to be clean and germ-free.

When to Test Pool Chlorine

Test chlorine levels two to three times a week, or more often after a storm or heavy pool use.

How to Adjust Chlorine Levels

Pool chlorine comes in liquid, granular or tablet form. If you’re not sure what form of chlorine distribution is best for your swimming pool and your pool maintenance routine, talk to a pool service technician.

If the chlorine level is low, add chlorine in your preferred method.

High levels of chlorine might occur if you’ve added too much or your pool is in the shade. In most cases, the sun will soon burn off high chlorine levels. Adding a chlorine neutralizer is another option, but you should be aware that this product will also affect the pool’s pH. 

What is pH?

pH is the measurement of the acidity or alkalinity of the water in your swimming pool, measured on a scale from 0 to 14.

Why is Balanced pH Important?

Chlorine disinfects best when water pH is balanced. When pH is too high, chlorine can’t kill germs as effectively. Low pH doesn’t affect the cleaning ability of chlorine. However, it can increase chlorine levels, which can cause skin and eye irritation in swimmers and corrode pool equipment.

Optimal pH Levels

A pH level of 7 is considered neutral, while levels below 7.0 are acidic, and above 7.0 are alkaline. A pH level between 7.2 and 7.8 is ideal for swimming. Some pool experts tighten this range even further, to between 7.4 and 7.6.

When to Test pH Levels

Test the pH levels of your pool water at least once a week - more often if it has rained or you’ve been swimming a lot. With regular pool water testing, you can spot changes and make adjustments before they become a problem.

How to Adjust pH Levels

When the pH of your pool water is too high or too low, it can irritate the skin and eyes and reduce the ability of your chlorine to effectively sanitize your pool. Water with unbalanced pH also could begin to corrode your pool equipment. As a swimming pool owner, know how to properly test and adjust your pool’s pH levels as part of your overall pool maintenance regimen.

What is Alkalinity?

Alkalinity and pH work together. Alkalinity helps keep your pH balanced, even when other chemicals are added that could affect pH.

Why is Balanced Alkalinity Important?

High alkalinity can cause high pH, cloudy pool water, reduced circulation and clogged filters. Low pool water alkalinity can cause eye and skin irritation and damage pool surfaces and equipment. When alkalinity is low, it also can’t “protect” your pool’s pH, resulting in dramatic swings in pH levels.

Optimal Alkalinity Levels

Pool experts recommend keeping alkalinity levels between 80 and 120 parts per million (ppm), although some testers consider a range from 100 ppm to 150 ppm acceptable.

When to Test Alkalinity Levels

Test pool water alkalinity levels weekly to ensure pH levels remain stable.

How to Adjust Alkalinity

Dry granular muriatic acid brings high alkalinity down, according to Pool School. Add a little at a time and wait a few hours before testing again or getting back into the water.

What is Calcium Hardness?

Calcium hardness refers to the amount of calcium carbonate in your swimming pool water. When calcium isn’t present in the water at the right level, it must be added.

Why Are Balanced Calcium Hardness Levels Important?

“Soft” water, or water with a low calcium level, can leach calcium from pool surfaces like plaster, pebble, tile grout, stone, cement and even fiberglass, according to Trouble Free Pool. Low calcium levels also can corrode metal parts like handrails, pipes and equipment. Low calcium levels in your spa may result in foamy water.

At the other extreme, high calcium levels can stain pool surfaces, irritate your skin and eyes, cause cloudy water and scale on pool rails and inside pipes and filters.

Keeping calcium hardness in balance protects your pool surfaces and equipment.

Optimal Hardness Levels

For plaster or fiberglass pools, it's best to keep hardness levels between 200 and 400 ppm. Fiberglass pools can handle a range between 100 and 330 ppm.

When to Test Water Hardness

Test your water hardness levels once a month.

How to Adjust Calcium Hardness

You may experience low levels of calcium in your pool water after a heavy rain or a heat wave. Increase calcium hardness by adding calcium chloride or calcium chloride dihydrate to the water.

What is Pool Stabilizer?

Pool stabilizer goes by several names, including pool conditioner, chlorine stabilizer and cyanuric acid (CYA). Its job is to help keep chlorine at consistent levels. It can come from three sources: stabilized chlorine (like dichlor or trichlor), liquid stabilizer and powder stabilizer. If you use stabilized chlorine, which already has stabilizer in it, you don’t need to add more stabilizer separately.

Why is Pool Stabilizer Important?

Chlorine stabilizer is like sunscreen for your pool, preventing the sun from burning off your chlorine. This protection helps manage your chlorine use throughout the swim season, saving you money on chemicals.

If you use a non-chlorine sanitizer, like bromine, you don’t have to worry about stabilizers.

Optimal Cyanuric Acid Levels

Cyanuric acid levels between 30 and 50 ppm will help keep your chlorine from breaking down before it has a chance to sanitize your pool water. Keep free chlorine levels at 7.5% of your cyanuric acid levels, advises Swim University.

When to Test Stabilizer Levels

You might only need stabilizer at the beginning of the swim season. Very heavy rainfall or excessive evaporation due to high temperatures may affect your stabilizer levels.

How to Adjust Stabilizer Levels

To raise CYA levels, add stabilized chlorine or cyanuric acid to your pool. Alternatively, you can use baking soda as a pool stabilizer, notes The Spruce, but that will also raise your pool’s alkalinity.

Reduce stabilizer levels by draining some pool water and replacing it with fresh water.

As with any new process, there is always a learning curve. These additional tips and safety measures from pool experts can help you master pool chemical maintenance.

• Wear protective gloves and goggles when handling pool chemicals, especially liquid chemicals.

• Don’t mix chemicals together outside of the pool.

• Keep the pool pump and filter running while adding chemicals.

• Add chemicals a little at a time; don’t overdo it. You can always add more later if needed.

• Wait at least 20 minutes after each chemical before adding more.

• Wait at least an hour before retesting and making further adjustments.

• Wait at least one to eight hours before going back into the pool, depending on the chemical added.

Keeping pool water chemicals in balance helps ensure a safe and comfortable swim experience. It also helps protect your pool and pool equipment.

With frequent testing, you can spot changes and make adjustments before they become a problem. Find the testing method that works best for you so you can continue to ensure a safe and enjoyable swimming experience all summer long.

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