Chlorine is a chemical that is widely used to sanitize pools and keep them free of harmful bacteria and algae. However, chlorine can also affect the pH level of the water, which is a measure of how acidic or basic it is. The pH level of pool water is important for several reasons, such as:
- Maintaining the comfort and safety of swimmers
- Protecting the pool equipment and surfaces from corrosion or scaling
- Enhancing the effectiveness of chlorine and other sanitizers
The ideal pH range for pool water is 7.4 to 7.6, which is slightly basic and close to the natural pH of human tears. If the pH level is too low (below 7.2), the water becomes acidic and can irritate the eyes, skin, and mucous membranes of swimmers. It can also corrode the metal parts of the pool and cause plaster or vinyl surfaces to deteriorate. If the pH level is too high (above 7.8), the water becomes basic and can cause cloudy water, scaling, and reduced chlorine efficiency.
How Does Chlorine Affect pH?
The answer to the question “Does chlorine raise pH” depends on the type and form of chlorine that is used to sanitize the pool. Chlorine comes in different forms, such as:
- Liquid chlorine (sodium hypochlorite)
- Granular chlorine (calcium hypochlorite)
- Tablet chlorine (trichloroisocyanuric acid or dichloroisocyanuric acid)
- Saltwater chlorine (generated by a saltwater chlorinator)
Each form of chlorine has a different pH level and reacts differently with the pool water. Some forms of chlorine tend to raise the pH level, while others tend to lower it.
Liquid Chlorine
Liquid chlorine is a common form of chlorine that has a very high pH level of around 13. When liquid chlorine is added to pool water, it breaks down into hypochlorous acid (the active form of chlorine that kills bacteria) and sodium hydroxide (a strong base that raises the pH level). Therefore, liquid chlorine tends to increase the pH level of pool water over time.
Granular Chlorine
Granular chlorine is another common form of chlorine that has a high pH level of around 11. When granular chlorine is added to pool water, it breaks down into hypochlorous acid and calcium hydroxide (another strong base that raises the pH level). Therefore, granular chlorine also tends to increase the pH level of pool water over time.
Tablet Chlorine
Tablet chlorine is a popular form of chlorine that has a very low pH level of around 3. When tablet chlorine is added to pool water, it breaks down into hypochlorous acid and either trichloroisocyanuric acid or dichloroisocyanuric acid (both strong acids that lower the pH level). Therefore, tablet chlorine tends to decrease the pH level of pool water over time.
Salt Water Chlorine
Saltwater chlorine is a form of chlorine that is generated by a saltwater chlorinator, which uses electricity to convert salt (sodium chloride) into chlorine gas. The chlorine gas then dissolves in the pool water and forms hypochlorous acid and sodium hydroxide. Therefore, salt water chlorine has a similar effect on pH as liquid chlorine, and tends to increase the pH level of pool water over time.
How to Balance pH and Chlorine in Pools?
Since different forms of chlorine can have different effects on the pH level of pool water, it is important to monitor both parameters regularly and adjust them as needed. The recommended levels for both pH and free chlorine (the amount of active chlorine available in the water) are:
- pH: 7.4 to 7.6
- Free chlorine: 2 to 4 ppm (parts per million)
To measure the pH and free chlorine levels in pool water, you can use test strips, test kits, or digital testers. You should test your pool water at least once a week, or more often if you use your pool frequently or have heavy rainfall or debris in your pool.
To adjust the pH level in pool water, you can use either pH increasers or pH decreases, depending on whether your pH level is too low or too high. Some common products that are used to raise or lower the pH level are:
- To raise pH: sodium carbonate (soda ash) or sodium bicarbonate (baking soda)
- To lower pH: sodium bisulfate (dry acid) or muriatic acid (hydrochloric acid)
To adjust the free chlorine level in pool water, you can use either shock treatments or stabilizers, depending on whether your free chlorine level is too low or too high. Some common products that are used to increase or decrease the free chlorine level are:
- To increase free chlorine: any form of chlorine, such as a liquid, granular, tablet, or salt water chlorine
- To decrease free chlorine: sodium thiosulfate (chlorine neutralizer) or sodium sulfite (chlorine reducer)
When adding any chemicals to your pool water, you should always follow the manufacturer’s instructions and safety precautions. You should also wait at least a few hours before testing your pool water again, to allow the chemicals to circulate and dissolve properly.
Conclusion
Chlorine is an essential chemical for sanitizing pools and keeping them safe and clean. However, chlorine can also affect the pH level of pool water, which is a measure of how acidic or basic it is. The pH level of pool water is important for maintaining the comfort and safety of swimmers, protecting the pool equipment and surfaces from damage, and enhancing the effectiveness of chlorine and other sanitizers.
Different forms of chlorine can have different effects on the pH level of pool water. Some forms of chlorine, such as liquid, granular, and salt water chlorine, tend to raise the pH level over time. Other forms of chlorine, such as tablet chlorine, tend to lower the pH level over time. Therefore, it is important to monitor both the pH and free chlorine levels in pool water regularly and adjust them as needed.
The ideal pH range for pool water is 7.4 to 7.6, which is slightly basic and close to the natural pH of human tears. The ideal free chlorine range for pool water is 2 to 4 ppm, which is enough to kill bacteria and algae without causing irritation or damage. To measure and adjust the pH and free chlorine levels in pool water, you can use various products and methods, such as test strips, test kits, digital testers, pH increasers, pH decreasers, shock treatments, and stabilizers.
By keeping your pool water balanced in terms of pH and free chlorine, you can enjoy a safe and comfortable swimming experience.