Pool Water Chemistry 101

image of pool supplies for a pool water chemistry blog post

Everyone wishes that they could fill their pools with water and never have to worry about anything. However, that’s just not how things are. You have to think about pool water chemistry, test the water, and add chemicals regularly. Though it’s time-consuming, it’s important to keep it free of pollutants.

Left unkempt, your pool can get infested with algae or become imbalanced which can lead to you needing to drain it and start over. Keeping your pool sanitized isn’t necessarily fun, but you only need some basic chemistry 101 help, the right supplies, and equipment, and want to ensure that your pool is swimmable and clean.

The Key to Having a Clean Swimming Pool

You can fill the pool with clean, freshwater, vacuum, and skim it every day, and still, the water is going to get dirty. Debris, such as twigs and leaves, can fall inside, and bugs take swims in it, too. Each time someone swims, they’re leaving behind dead skin, hair, body oil, soap, and shampoo.

The only thing keeping the contaminants from hurting the pool’s pH level is sanitizers and other chemicals. For it to be effective, you’ve got to focus on pH, alkalinity, and even calcium hardness.

Pool chemicals are used to clear the water, treat algae, and prevent staining if hard water is an issue where you live.

Pool Water Chemistry 101

Balancing Levels Through Pool Water Chemistry

To protect your pool and your skin, you should test your pH and alkalinity levels once a week with a home test kit or testing strips. Always keep a pH increaser, pH reducer, and alkalinity increaser on-hand to ensure that your pool water levels stay balanced. 

The alkalinity increaser should increase both alkaline and pH levels as needed, while the pH decreaser will lower both pH and alkalinity. You may have to try a few different measurements and combinations until you find the perfect amount for your water.

As long as your pool water is balanced at all times, the chlorine will work more effectively. It also helps to protect the pool itself from excess wear and tear as well as scaling and other damage.

Understand pH, Alkalinity, and Calcium Levels

The pH level in your pool water needs to be balanced to avoid becoming too acidic. Ideally, the pH level of the water should be somewhere between 7.4 and 7.6. You can easily test your water with a kit and use a pH increase when needed.

Another crucial part of pool water chemistry is the alkaline levels. These levels should be between 100 to 150 ppm, and alkaline serves as a pH buffer to keep the levels in check. Alkalinity increaser can also help you maintain the proper levels in your pool.

Finally, calcium hardness is important since it can mess up your plaster or lining if levels are too high. The calcium hardness should be between 170 and 300 ppm, and you may add calcium hardness to protect your walls and equipment.

pH Level

When it comes to pool chemistry, you have to consider pH levels. This is a measurement of the acidity or basic-ness of the substance. The scale goes from 0 to 14, and 7 is neutral. If the number is below 7, it’s acidic.

Anything entering the pool’s water can affect pH levels. Dirt, rain, people, leaves, and other things can make such changes. Therefore, you want to keep your pool pH level at optimal range. Ensure that pH decreasers and increasers are on hand. You are probably going to use less pool decreaser, but keep it available. Make sure the pool has a pH level between 7.4 and 7.6 so that you don’t have to add more pool chemicals.


This pool chemical is there to prevent the Ph from going up or down drastically, so it’s a buffer and absorbs major changes to your pool before they affect pH.

Keep the alkalinity steady by using a total alkalinity increaser. Baking soda works well here. If both the pH and alkalinity are low, baking soda is going to raise both for total alkalinity power.

Calcium Hardness

Calcium hardness is a measurement of how soft or hard the water in the pool is, and it can vary based on your water source and where you live. Well water often has higher minerals than what comes from the spigot. If calcium levels are too low in the pool, it can cause corrosion and scaling of the pool equipment and walls. Use a calcium increaser here.

When calcium levels are too high, you could have a cloudy pool. Shocking your pool can help and promote water balance. A high pH can cause calcium hardness in the pool. Ensure that you’ve adjusted alkalinity and then pH when performing pool maintenance.

Sanitizing Your Pool

In order to keep your pool safe and clean, you need to add specific chemicals to the water. Chlorine is the most commonly used, but you can also use salt, stabilized chlorine, and other minerals depending on how your pool is set up.

Ideal chlorine levels should be between one to 3 ppm. This chemical is extremely effective at killing algae and bacteria, and it’s also very affordable. 

To add chlorine to your pool water, you can use chlorine tablets, powder, granules, or a salt-chlorine generator. This process takes regular table salt and turns it into chlorine, making the water softer and “less harsh” on the eyes, hair, and skin.


Regardless of the one you choose, sanitizers may keep your pool fresh. Therefore, there aren’t any viruses, bacteria, and algae that can grow. There are multiple options available:


A popular pool sanitizer is chlorine because it doesn’t cost much and is highly efficient. Chlorine can sanitize the pool by oxidizing the contaminants. It enters the molecules and destroys them. You’re going to find that chlorine kills algae, bacteria, and viruses.

You may find chlorine in two forms:

  • Granules – With granules, you pour them into the pumps and filters, and they dissolve and go throughout the filtration system. This method isn’t very effective, and it’s time-consuming. Plus, the chlorine might not get distributed evenly, so some non-sanitized water can stay.
  • Tablets – You can get chlorine tablets in 1- or 3-inch sizes. Just add them to your floating chlorine dispenser, an automatic chlorinator, or the pool’s skimmer basket to help with water chemistry.

Regardless of how you use chlorine tablets, they’re going to get distributed more evenly. However, it’s recommended to utilize an automatic chlorinate for better dispersion rates to refresh your pool water efficiently.

The ideal chlorine levels for pool water is three parts per million. If you use less than that, the water isn’t really fresh, and if you utilize more, you’re going to need a chlorine neutralizer to bring levels down and keep the pool clean. You can find two neutralizers available:

Stabilized Chlorine

If you have an outdoor swimming pool, you should use stabilized chlorine so that the sun doesn’t burn off the extra stuff. It includes cyanuric acid, which is a known pool stabilizer.

Cyanuric acid protects the chlorine, allowing it to stay in the water up to five times longer. Therefore, you don’t have to replace it as often, reducing the amount of pool maintenance you need to do.

Unstabilized Chlorine

With unstabilized chlorine, the sun can penetrate it and burn it out of the water. Ensure you’ve added more chlorine to the pool often, which can cost more money. It works well for indoor pools and can be used for pool shock. You’re supposed to shock your pool at night, so there isn’t a worry about the sun.

Other Pool Chemistry Chemicals You Need to Know About

Water balance is a real thing, and you may need to add various chemicals before your pool party. As a pool owner, it’s up to you to ensure that everything is properly balanced. For some things, you can use test strips to determine the levels and numbers, such as for alkalinity, pH, and chlorine.

Most pool owners aren’t going to use salt to keep the water balanced for swimming. However, most pools can have chemicals to maintain the ideal pH and ensure everything else is right.

This can include algaecide to keep the water balanced and prevent algae from growing. Another chemical to try is a clarifier or flocculant. They’re separate chemicals and somewhat do the same thing. The major difference is that one treats the cause while the other only treats the symptom.

Bromine is something else to consider and ionizes contaminants. The benefit of bromine is that it doesn’t break down so fast. However, it creates waste products, reducing the effectiveness of the bromine.

Using Chemistry to Keep Your Pool Clean

Knowing how to keep your pool clean and chemically balanced keeps your water fresh and ready for fun. It’s important to use the right chemical sequence, which protects the pH so that it doesn’t get too high. Ultimately, you can’t completely rid your pool of debris, but it can free up your time to go back to enjoying the fun.

When you know the basics of pool water chemistry, it’s easy to ensure that your water and pool are protected. Use a test kit or strips to check water weekly and add the specific chemicals as needed.

If you would like a professional to help keep your water balance, you can learn more about our swimming pool service to have a cleaner and more sanitary pool. If you would like us to come out and balance your pool water contact us today!