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Differences Between pH and Alkalinity in a Pool or Hot Tub

If you have a swimming pool or a hot tub at your home, you already know the importance of pH and alkalinity levels. But many people often confuse them with each other. Maybe you also don't have much idea about what’s the difference between pH and alkalinity in a pool or hot tub?

There are some significant differences between pH and alkalinity. pH measures how acidic or basic the pool water is. On the other hand, alkalinity measures your pool’s ability to resist the changes in pH. So, maintaining the pH and the alkalinity levels of water is necessary for your pool.

That being said, if you want to maintain your pool properly, you must know about all the differences between pH and alkaline levels of water. Both of them have different effects on your pool health. Having a clear idea about them, you can control them easily. So, without further ado, let's get right on with the facts. 

What is pH?

pH is in short for ‘power of Hydrogen’ and it refers to the hydrogen ion concentration in a given solution. The amount of this concentration in a substance actually contributes to the specific nature of that substance.

This scale indicates how basic or acidic something is. The scale goes from 0 to 14. As the value goes closer to zero, the solution becomes more acidic. If it goes closer to 14, the solution becomes more basic. The scale is logarithmic so each level on the scale is an increase of 10 times.

The pH level of pure water is 7. So, pure water is neither acidic nor basic. This should be the case for your pool also. The ideal pH level for pool water is 7.2-7.3. This slightly basic pH level is perfect for pools and hot tubs as it is closer to the pH level of our bodies.

Effects of pH on a Pool

pH levels affect your pool in various ways. High and low pH levels have separate effects on water. Now I’ll talk about them individually.

High pH level: High pH levels make the water more basic. This damages our body cells and causes irritation to the skin, eyes, and other sensitive organs. It also makes the pool water cloudy. High pH levels also reduce chlorine effectiveness. There might be stains on metal components and scaling on pool walls because of the high pH level of water.

Low pH level: Low pH levels are also bad for pools. As the water gets more acidic, it corrodes any metal parts like rails and ladders. It also damages the pool liners and etches plasters. Acidic water is also harmful to our skins as it can cause severe irritation to our sensitive body organs. Also, lower pH levels tend to lower the total alkalinity of the pool.

Why is pH Important in a Pool?

pH level is important for your pool because it determines how acidic or basic your pool water is. Unbalanced pH will hinder the lifespan of your pool in the long run.

That is why managing pH levels should be one of your main concerns during pool maintenance. You should check your pH levels every few days or a week, and adjust them to the desired level if required. pH levels also influence the effectiveness of chlorine. As we know, chlorine kills the germs and bacteria in the pool, so unbalanced pH can make your pool unhealthy.

pH levels also contribute to the longevity of the pool’s other components. Fluctuating pH levels can damage these other parts severely so you have to spend money to replace them. So, to ensure the overall quality of your pool, you must maintain a balanced pH level.

What is Alkalinity?

Alkalinity is a measurement of the concentration of all the alkaline substances present in a solution. It is measured using the unit ppm or parts per million. Alkaline substances are basic in nature.

The alkalinity of water measures the buffering capacity of that water. Buffering capacity refers to the ability of water to withstand a change in pH level. The alkaline substances you can commonly find in a pool are bicarbonate, carbonate, and hydroxides. They can neutralize acids. So, they act as a buffer on the swimming pool and keep the pH levels of water from changing.

Usually, as the alkalinity level of the water increases, the resistance to a change in pH level also increases and vice versa. The optimum level for alkalinity is 80 to 120 ppm. This also depends on what kind of chlorine you’re using. If you’re using chlorine with low pH like Trichlor, then you should aim for 120 ppm. But, with high pH chlorine, the range should be from 80-100 ppm.

Effects of Alkalinity on a Pool

Alkalinity levels are very important for the well-maintenance of a pool. If they are unbalanced, they will cause damage to your pool. So, you must control alkaline levels.

High Alkaline level: High alkaline levels are not as bad as low alkaline levels. But, it can also cause various problems. High alkalinity levels make the water murky and cloudy. It clogs the pipes and the filters, so water circulation gets reduced. Another problem is, you can't change the pH level easily as you desire. So, additional costs are needed if you’d like to change that.

Low Alkaline level: Low alkaline levels can damage your pools significantly. The pH level fluctuates easily with a lower alkaline level. So, it’s hard to keep the water balanced. The water often becomes more acidic, resulting in itchy dry skin and irritation on the sensitive body parts.

Lower alkaline levels also damage the pool walls and other parts as well. The pool walls can crack if the alkaline levels are low for a long time. It also results in the corrosion of metal components like pipes, filters, and rails. It also reduces the effectiveness of chlorine and other pool sanitizers. So, you must take quick action to adjust your alkaline levels if it’s low.

Raising Alkalinity in Your Pool

Alkalinity levels are very important for your pool. Most of the time, alkalinity becomes too low. You can find it out by checking your pH level. If the pH level is drifting, then your alkalinity level is most probably low. You need to increase the alkalinity level as soon as possible. Using alkaline products will help you do it.

One of the easiest ways to raise the alkalinity level of your pool is to use sodium bicarbonate or baking soda. It is one of the most used compounds in the pool industry. You can buy substances like Alka-plus, Alka-buffer, and various other alkaline products to use in your pool. Just make sure they contain sodium bicarbonate in them.

You have to use baking soda carefully though. A general rule is to use 1.5 pounds of baking soda for every 10,000 gallons will increase the alkalinity by 10 ppm. So, if your pH level is below 7.2, you might need to add 3 to 4 pounds of baking soda.

Lowering Alkalinity in Your Pool

Sometimes you might need to lower your alkalinity level. Because high alkalinity will make it very difficult to adjust your pH level. If you want to lower your alkalinity, you need to add more acid like muriatic acid to the water. But, there’s a problem. This procedure will also decrease the pH level along with the alkalinity level. So, you’ve to work around this problem.

To solve this problem, you have to follow the right procedure. First, add acid until you get to your desirable alkalinity level. You don’t need to worry about your pH level during this. Just remember to dilute the acid in water first and then pour it all over the pool.

Once you get your desired alkalinity level, you need to increase your pH level. But, you have to raise the level while making sure the alkalinity is unchanged. To do this you have to aerate the pool. By doing this, you can easily increase your pH level without raising the alkalinity level.

Relation Between pH and Alkalinity

While pH levels determine the nature of your pool water, alkalinity determines the stability of pH levels in your pool. So, lower alkaline levels will make the pH levels fluctuate easily and the water level is more likely to be acidic because of it.

Once you’ve achieved the correct pH level in your pool, you should also increase the alkalinity of the water. Thus, the nature of the water won’t change in a long time. It will ensure the healthy quality of your pool.

Managing pH and Alkalinity of Your Pool

The first thing to do is to call professionals to manage your pool’s pH and alkalinity levels. After that, you should check your water pH level regularly.

As you already know that pH levels and alkalinity levels can affect each other. So, make sure to keep them in balance. Every time you raise or lower any of the two, make sure to do the same for the other as well to keep the balance.

Understanding pH and alkalinity is a must for any pool owner. Both pH levels and alkaline levels are crucial for the maintenance of a swimming pool or hot tub. But most people don't have a clear understanding of these factors. So, in this article, I tried to explain what’s the difference between pH and alkalinity in a pool or hot tub?

You should be able to monitor these levels in your pool more easily now. Thanks for stopping by. Wish you all the best.

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Written by Ferdi Vol
Ferdi Vol is a pool and hot tub owner who has been working in this industry for over 5 years. He has learned all the ins and outs of maintaining pools and hot tubs, as well as how to privately own one. Ferdi Vol is also passionate about blogging, researching topics that he shares with his readers online via this blog.
About Ferdi Vol
About Pool Uncle
Pool Uncle is a blog that focuses on helping pool and hot tub owners get the right tools, maintain their pools and hot tubs, and learn about how to care for them. It provides readers with all of the information they need to keep their pools clean, safe, and looking great. The website also publishes original articles about pool maintenance topics such as filtration systems or algae prevention techniques.
About the Author
Ferdi Vol has been in the swimming pool and hot tub as an owner for over 5 years. His experience ranges from owning a pools and hot tubs and maintaining them. He’s learned about pumps, filters, chemicals, cleaning products, treatment systems… you name it!
About Ferdi Vol
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