As a pool owner, you are always worried about the safety of your family and guests using the pool. Besides regular cleaning, it also needs to have a chemical balance for effective disinfection and to prevent any damage to the pool’s surfaces and equipment.
Decreasing alkalinity in the pool is a part of this process. High alkalinity can lead to a host of issues, including imbalanced pH, scale buildup in the pool, and reduced chlorine effectiveness. So if you don’t want these problems to ruin your enjoyment, this pool guide will come in handy.
However, before we dive deep into the practical steps, here is a brief introduction to what alkalinity is and why it’s important to keep it balanced.
What Is Total Alkalinity?
Total alkalinity is the measure of pool water’s ability to neutralize acids. It helps maintain a pH that is safe for swimming. While 7.4 is an ideal pH for pools, anything between 7 and 7.6 is acceptable.
Alkalinity refers to the amount of alkaline salts, including carbonates, bicarbonates, and hydroxides present in the total volume of water. The recommended concentration for these salts ranges from 100 to 150 ppm. In case you fail to keep your pool’s alkalinity within this range, its overall chemistry will be disturbed.
Why Is It Important To Balance Pool Alkalinity?
Balanced pool alkalinity is essential for different reasons. However, the major reason is its direct impact on the water’s pH. The greater the amount of alkaline substances, the higher the pH and vice versa.
If the pool’s pH drops lower than 7, it will cause dry hair, skin irritation, a stinging sensation in the eyes, and respiratory discomfort. Because of acidic pH, the pool surfaces, filters, and other equipment corrode faster than usual.
The presence of alkaline salts stabilizes the pH and helps prevent abrupt changes. Technically, they act as a buffering agent that resists the rapid fluctuations in pH. Therefore, it’s important to maintain proper alkalinity levels in your pool.
What Happens If A Pool’s Alkalinity Is Too High?
Though low pH has negative effects on your health and the pool’s environment, high pH also has its own consequences. For those who believe that maintaining a high alkalinity is better, it’s not always necessary, especially when your pool already has an optimum pH balance.
The excessive concentration of alkali ions may produce the following undesirable results:
Cloudy Water: The first sign of high alkalinity is the cloudy appearance of pool water. It usually happens when your alkalinity exceeds the strength of 200 ppm or the pH goes beyond 7.8. The pool doesn’t only look unattractive but becomes unfit for regular use.
Physical Irritations: You will experience skin rashes, irritation, and burning eyes when diving in a pool with high alkalinity. Staying in contact with highly alkaline water for a longer time also affects your respiratory health.
Surface Scaling: As mentioned above, high alkalinity refers to the increased concentration of alkaline salts, including calcium carbonate. The increased calcium starts depositing along the water lines, causing scaling.
Clogged Filters: When calcium level rises, it tends to precipitate and collect on membranes, resulting in clogged filters. This in turn forces the filtration system to overwork, causing reduced efficiency and potentially leading to premature burnout.
Decreased Sanitization: Chlorine, the common disinfectant in pools, becomes less effective at high pH. Due to its reduced activity, the pool water isn’t properly sanitized, making you vulnerable to various harmful microorganisms.
Chlorine, when dissolved in pool water, produces 2 chemical species; hypochlorous acid and hypochlorite ions. Hypochlorous acid is the active species responsible for killing pathogens.
As pH increases, the equilibrium between hypochlorous acid and hypochlorite ions shifts, resulting in a higher proportion of hypochlorite ions and a lower proportion of hypochlorous acid, as mentioned in the chart below:
| pH | % of Active HOCL |
| 6.0 | 97 |
| 6.5 | 91 |
| 7.0 | 76 |
| 7.2 | 66 |
| 7.5 | 50 |
| 7.8 | 33 |
| 8.0 | 24 |
| 8.5 | 9 |
Now, the fact is established that high alkalinity isn’t always beneficial. And you may experience some unpleasant effects if it exceeds the recommended range. The next section will tell you about the potential factors that lead to high alkalinity and how you can maintain a balance.
What Causes High Alkalinity In Pools?
There are multiple factors that contribute to increased alkalinity and pH of pool water. While some factors are uncontrollable, others are manageable with proper pool maintenance.
The factors affecting pool pH and causing high alkalinity are:
- Overusing pool stabilizers, algaecides, and certain pH increasers
- Contaminants such as body lotion, sunblock, and sweat from swimmers
- Certain types of rainwater, especially in areas with limestone or chalk
- Using water with naturally high alkalinity to fill or top off the pool
- Adding chemicals such as sodium bicarbonate (baking soda) to adjust pH and alkalinity
- Frequently using chlorine-based pool shocks
- Inefficient working of the filtration system
- Not regularly testing and adjusting the water chemistry
How To Reduce Alkalinity In A Pool?
You have two different chemicals to lower pool alkalinity; muriatic acid and sodium bisulfate. There is no rule of thumb when choosing an alkalinity reducer for the pool. You can use whatever is easily available at the moment. However, the method of application may vary slightly for each based on their chemical nature.
Muriatic Acid As An Alkalinity Reducer
Muriatic acid is a diluted form of hydrochloric acid with concentrations typically in the range of 20–25%.
Remember that this strength may vary from brand to brand. It’s commonly used in pool maintenance to lower alkalinity and pH, hence it’s easily available at local hardware or home supply stores.
Steps For Preparation:
- Wear protective gear (gloves, goggles, and long sleeves) as muriatic acid is highly corrosive.
- Ensure proper ventilation if you are working indoors or in an enclosed space.
- Turn off your pool pump 1–2 hours before you start adding acid.
How To Use:
- Measure the current alkalinity level using a pool test kit and note the readings.
- Refer to the manufacturer’s guidelines or an online calculator to determine the correct amount of muriatic acid based on your pool size and reading.
- Film a plastic bucket with pool water and slowly add the calculated amount of muriatic acid to the water in the bucket. Always add acid to water, not water to acid, to prevent splashing.
- Carefully pour the diluted muriatic acid into the deep end of the pool. Walk around the perimeter of the pool, pouring the solution slowly for even distribution.
- Let the pool pump run continuously for at least 4–6 hours to circulate the acid and ensure it mixes thoroughly with the pool water.
- After allowing sufficient time for the acid to circulate, use the pool test kit to measure the alkalinity again. If the alkalinity is still above the desired range, repeat the process in small increments to avoid overcorrection.
Other Applications:
Besides reducing alkalinity, muriatic acid is also effective against calcium deposits in the bottom of pools, removing stains on concrete, and cleaning filters.
Sodium Bisulfate As An Alkalinity Decreaser
Sodium bisulfate, also known as dry acid, is a safer alternative to muriatic acid for lowering alkalinity in pools. While it is still a strong acid, it is less corrosive, making it easier and safer to handle. The only concern about using dry acid is its higher cost compared to muriatic acid. However, considering the reduced risks and the ease of use, many pool owners find that the added expense is justified by the safety and effectiveness it offers.
Steps For Preparation:
- While sodium bisulfate is less corrosive, it’s still important to protect yourself by wearing gloves, goggles, and long sleeves.
- Keep the sodium bisulfate in a dry, cool, and well-ventilated area before and after use.
How To Use:
- Sodium bisulfate can be added directly to the pool without dilution.
- Slowly sprinkle the required amount into the deep end of the pool.
- Spread it evenly to ensure uniform distribution, avoiding areas near skimmers and return jets to prevent concentration in specific spots.
Alternative Method:
- If preferred, you can calculate the appropriate amount of sodium bisulfate needed for your pool’s volume and dissolve it in a bucket of pool water.
- Once fully dissolved, carefully pour the mixture into the deep end of the pool, distributing it evenly.
Precautions To Consider When Decreasing Alkalinity In Pools
Does it sound too simple to add acidic compounds to lower pool alkalinity? Well, it might not be. You can’t just take the alkalinity decreaser and dump it all into your pool. It requires proper testing to know the current alkalinity and pH levels and to determine how much acid is needed to reduce the alkalinity in the pool.
- Never add too much alkalinity decreaser at first use. Always start with a smaller amount and adjust as needed.
- Wait at least 4-6 hours after adding acid before retesting the water to allow for proper mixing.
- Continue to test the pool water regularly to ensure alkalinity remains within the ideal range.
- Keep a record of chemical adjustments to track changes and improve future maintenance.
Final Thoughts
Maintaining the correct alkalinity in your pool is crucial for both the longevity of your pool equipment and the safety of swimmers. While lowering alkalinity may seem daunting, with the right approach you can achieve optimal water balance.
Remember, every pool is unique, so regularly test your water and make adjustments as needed. By following these guidelines, you ensure that your pool remains a safe, enjoyable, and crystal-clear oasis for everyone.
FAQs
How To Bring Alkalinity Down?
To bring alkalinity down in your pool, add muriatic acid or sodium bisulfate (dry acid) in small amounts. However, be mindful that this process can also lower the pH level, so it’s important to monitor and adjust the pH after lowering the alkalinity to maintain the proper balance. Always retest the water after treatment to ensure both alkalinity and pH levels are within the recommended ranges.
Will Lowering Alkalinity Lower pH?
Yes, lowering alkalinity will also lower pH since they are closely related. To reduce alkalinity without significantly lowering pH, you can aerate the pool water after adding acid. This process raises the pH back up without affecting the alkalinity.
Is It Safe To Swim In A Pool With High Alkalinity?
No, it’s not safe to swim in a pool with high alkalinity. High alkalinity doesn’t only compromise your pool’s integrity but poses health risks. Swimming in a pool with high alkalinity can lead to eye and skin infections. Additionally, it reduces the effectiveness of chlorine, further increasing the risk of bacteria and algae growth. Therefore, it’s essential to address high alkalinity before using the pool for a safe and pleasant swimming experience.
Can You Use Baking Soda To Lower Alkalinity?
No, baking soda is not used to lower alkalinity; in fact, it increases it. Both baking soda and soda ash are alkaline substances, so adding them to your pool will raise both the alkalinity and pH levels.
What Is The Best Product To Lower Alkalinity In A Pool?
Muriatic acid is one of the most effective products for lowering alkalinity in a pool. However, it must be used with caution due to its potency. Based on typical guidelines, you would add about 1 quart of muriatic acid for every 10,000 gallons of water to reduce the alkalinity by approximately 10 parts per million (ppm). Remember to always dilute the acid before adding it to the pool, usually with a 10:1 water-to-acid ratio, and add it gradually.