pH vs. Total Alkalinity and Their Relationship in Your Pool

I talk a lot about water chemistry and the importance of pH and Total Alkalinity (TA), but you may ask yourself, “What exactly do these terms even mean, and how do they interact with each other?” Well, in the world of pool maintenance, pH and alkalinity are closely linked and must work in synchronization to ensure the balance of the pool water and safety for swimmers.

In this article, I’ll dive into the intricate chemistry behind pH and Total Alkalinity, shedding light on their individual significance and how they affect your pool’s water quality. So, let’s dive in!

Main Takeaways

• If a pool is too acidic or alkaline, swimmers can experience respiratory distress and stinging red eyes.
• The ideal pH level for a swimming pool typically falls within the range of 7.2 to 7.8, while the recommended total alkalinity range for a swimming pool is typically between 80 and 120 parts per million (ppm).
• To make water more alkaline, you can use soda ash (sodium carbonate) or sodium bicarbonate (baking soda), and to make water more acidic, you can use muriatic acid or sodium bisulfate.

What Is pH?

pH stands for the “potential of hydrogen” and is known as the negative logarithm of H+ ion concentration. If that sounds like a bunch of nonsense to you, don’t worry. I will break it down for you below.

In a swimming pool, pH reflects the pool’s health as it measures the alkalinity or acidity of a substance (in this case, the water in a swimming pool). As a scale, pH ranges from 0 to 14, with 7 being neutral. pH below 7 is considered acidic, and pH above 7 is considered alkaline (or basic).

If the pool’s pH is too highly alkaline or acidic, swimmers can experience respiratory distress and stinging red eyes. That’s why you must stay in the ideal neutral zone when it comes to pH balance for swimmer safety. The ideal pool pH is slightly alkaline, between 7.2 and 7.6, with anything above 7.8 being too alkaline and anything below 7.2 being too acidic.

What Is Total Alkalinity (TA)?

Total alkalinity (TA) is another important water parameter to consider when maintaining a swimming pool. It is the measure of the water’s ability to neutralize acids or the water’s ability to resist changes in pH. In other words, TA acts like a buffer zone. It stabilizes pH levels in the water, preventing rapid and drastic fluctuations in pH, which could otherwise lead to discomfort for swimmers and problems with pool equipment.

As you can see, in a swimming pool context, TA is absolutely vital due to its ability to influence the efficiency of other pool chemicals due to its close relationship to pH.

How Does pH Influence Alkalinity?

pH and alkalinity in a pool are closely intertwined. The pH level can significantly impact the TA. Specifically, when the pH level is too high or too low, it can cause shifts in TA. A high pH tends to raise alkalinity, while a low pH can lower it. However, that is not to say it’s impossible to have high pH and low alkalinity or vice versa. 

How Does Alkalinity Influence pH?

Alkalinity itself doesn’t determine the pH value of your pool water. But its influence on pH stands all the same, as it helps prevent rapid pH changes when acids or bases are added to the water. TA’s influence thus also acts to stabilize water chemistry. It prevents wide fluctuations in pH levels: if the water’s alkalinity is too low, it can’t effectively neutralize acids. On the other hand, if the alkalinity in your pool is too high, it can impede pH adjustments, making it difficult for you to bring the pH levels to the desired range. However, while alkalinity can help buffer against pH changes, it doesn’t dictate the actual pH value.

Why Are pH and Total Alkalinity Important For Your Pool?

Maintaining both the pH and TA levels is absolutely vital to your pool’s health. If your pool’s pH is too low, it can lead to a host of problems, including skin and eye irritation, pool equipment corrosion, and pool surface deterioration. On the other hand, if the pH is too high, water can become cloudy, chlorine may not be as effective, and scale deposits may form on the surfaces of your pool! 

As you should know by now, alkalinity and pH are forever entwined. When TA is within the correct range, it prevents rapid fluctuations in pH and reduces the need for constant adjustments. This stability in pH ensures that your pool remains comfortable and safe for swimmers while prolonging the life of pool equipment and surfaces. Neglecting total alkalinity can result in pH swings, making it challenging to maintain the desired water balance and ultimately leading to the issues above.

Ideal pH and Alkalinity Levels in Pools

The ideal pH levels for a swimming pool typically fall within the range of 7.2 to 7.8, with the ideal pH being 7.4. This pH is necessary for swimmers’ comfort, effective sanitization, and to prevent scaling and corrosion. The recommended TA range for a swimming pool is typically between 80 and 120 parts per million (ppm).

How to Balance pH and Alkalinity

Phew! It is like being back in high school chemistry again! Trust me, I know more than anyone that pool chemistry can be a head-scratcher. But balancing pH and alkalinity is an essential skill for any pool owner. To summarize what we’ve learned so far:

• pH measures the acidity or alkalinity of water on a scale from 0 to 14, with 7 being neutral. Values below 7 are acidic, and values above 7 are alkaline. The ideal pH levels for a swimming pool typically fall within the range of 7.2 to 7.8. 
• Alkalinity measures the water’s ability to resist changes in pH. It is typically expressed in parts per million (ppm) and has a recommended range of between 80 and 120 ppm.

Here’s a quick step-by-step guide on how to balance the two.

Step One: Test the Water

Test and establish the current pH and TA levels of the pool using a fresh pool testing strip (or liquid testing kit, depending on what you prefer using).

Step Two: Adjust the Alkalinity

First, adjust the TA. Remember, if the alkalinity is too low, you should increase it using sodium bicarbonate. But if it’s too high, you’ll need to use muriatic acid or sodium bisulfate, which will also affect pH. Specific alkalinity adjuster products are also available if you’re seeking something highly specific. Ideally, dissolve the product in a bucket of water before adding it to the pool or tank to prevent random spot increases in alkalinity. You can use my pool alkalinity calculator to figure out which chemicals to add and how much.

Step Three: Adjust the pH

The next step is to adjust your pH levels if they’re still outside the recommended range of 7.2 to 7.8. To raise pH, you can use pH increasers such as soda ash (sodium carbonate) or sodium bicarbonate (baking soda). To lower pH, you can use pH decreasers like muriatic acid or sodium bisulfate. Be extremely cautious, especially when handling acidic chemicals—always wear proper safety gear and gloves. You can use my pool pH calculator to figure out which chemicals to add and how much.

Step Four: Mix and Test

Make gradual adjustments to both pH and alkalinity. Run your pump and filter to allow the water to circulate and blend, then wait at least 6 hours before retesting the water. Repeat the process until you achieve the desired pH and TA levels.

Step Five: Maintain the Necessary Levels

Keep testing your water regularly. You should test your pH 2 to 3 times a week, while you can get away with testing your TA just once a week. This will help you catch any imbalances early on and stop any extreme fluctuations in the chemical levels. 

Frequently Asked Questions

What should be adjusted first: alkalinity or pH?

Always adjust alkalinity first. Since it helps stabilize pH levels, adjusting it before allows you to prevent any fluctuations in the pH once you bring it up to speed.

Will pH be high if alkalinity is low?

No, not necessarily. Low alkalinity can contribute to pH fluctuations, but pH can be high, low, or within the desired range regardless of alkalinity.

What happens if pool alkalinity is too low?

If pool alkalinity is too low, the pH will become unstable, and the water may become acidic. This means it will be corrosive, making it dangerous for swimmers. The pool’s surface and equipment could become etched and damaged as well.

pH vs. Total Alkalinity: The Mystery Solved

As you can see, in the world of pool maintenance, the balance between pH and total alkalinity is a delicate dance, each playing a vital role in ensuring a pristine and safe swimming environment. Understanding and managing these two essential pool chemistry parameters is key to a clean and sparkling pool.

Do you have any lingering questions on water chemistry? Shoot me a message; I’ll be happy to help sort out any doubts you have about pool chemistry.