If you own a hot tub, you know how important it is to keep the water chemistry balanced. One of the key factors that affect the quality and safety of your hot tub water is the pH level. pH is a measure of how acidic or basic the water is, and it ranges from 0 to 14. A pH of 7 is neutral, while a pH below 7 is acidic and a pH above 7 is basic.
The ideal pH level for your hot tub water is between 7.4 and 7.6, which is slightly basic. This ensures that the water is comfortable for your skin and eyes and that the sanitizer (usually chlorine or bromine) works effectively to kill bacteria and other contaminants. If the pH level is too low (below 7.4), the water becomes corrosive and can damage your hot tub equipment, pipes, and shell. It can also irritate your skin, eyes, and respiratory system, and reduce the effectiveness of the sanitizer.
What Causes Low pH in Hot Tub Water?
There are several factors that can lower the pH level of your hot tub water, such as:
- Bather load: The more people use your hot tub, the more pollutants they introduce into the water, such as body oils, sweat, cosmetics, sunscreen, saliva, urine, etc. These substances can lower the pH level by consuming the sanitizer and creating organic acids.
- Rainwater: Rainwater is naturally acidic and can lower the pH level of your hot tub water if it gets into the tub. Rainwater can also bring in dirt, dust, leaves, and other debris that can affect the water chemistry.
- Water source: The water you use to fill up your hot tub may have a low pH level to begin with, depending on where you live and what kind of water treatment system you have. For example, well water or soft water may have a lower pH than tap water or hard water.
- Chemicals: The chemicals you add to your hot tub water can also affect the pH level. Some chemicals, such as chlorine and bromine, are acidic and can lower the pH level when they are added or when they react with contaminants in the water.
How to Raise pH in Hot Tub Water?
If your hot tub water has a low pH level, you need to raise it as soon as possible to prevent damage and discomfort. There are two main methods to raise the pH level in your hot tub water: using soda ash (sodium carbonate) or using baking soda (sodium bicarbonate).
Method 1: Using Soda Ash
Soda ash is the most common and effective way to raise the pH level in your hot tub water. Soda ash is a base that neutralizes the acidity in the water and raises the pH level quickly. You can buy soda ash from any pool or spa store or online.
To use soda ash to raise the pH level in your hot tub water, follow these steps:
- Test the pH level of your hot tub water using a test kit or test strips. You can also use a digital meter for more accuracy.
- Calculate how much soda ash you need to add based on the size of your hot tub and how much you need to raise the pH level. You can use this table as a guide:
| Hot Tub Size (gallons) | Amount of Soda Ash (ounces) per 0.2 increase in pH |
| 100 | 0.5 |
| 200 | 1 |
| 300 | 1.5 |
| 400 | 2 |
| 500 | 2.5 |
- Turn off the jets and heater of your hot tub and make sure the water is circulating.
- Add the required amount of soda ash to a bucket of warm water and stir well until dissolved.
- Pour the solution into your hot tub slowly and evenly around the edges.
- Wait for at least 15 minutes before turning on the jets and heater again.
- Test the pH level again after an hour and repeat the process if needed until you reach the desired range.
Method 2: Using Baking Soda
Baking soda is another option to raise the pH level in your hot tub water, but it is less effective than soda ash. Baking soda is also a base that neutralizes acidity in the water, but it also raises the total alkalinity (TA) level, which is a measure of how well the water can resist changes in pH. The ideal TA level for your hot tub water is between 80 and 120 ppm (parts per million).
If your TA level is too low (below 80 ppm), you can use baking soda to raise both the TA and pH levels at the same time. However, if your TA level is already within the ideal range or too high (above 120 ppm), you should avoid using baking soda, as it will raise the TA level too much and make it harder to adjust the pH level in the future.
To use baking soda to raise the pH level in your hot tub water, follow these steps:
- Test the pH and TA levels of your hot tub water using a test kit or test strips. You can also use a digital meter for more accuracy.
- Calculate how much baking soda you need to add based on the size of your hot tub and how much you need to raise the pH and TA levels. You can use this table as a guide:
| Hot Tub Size (gallons) | Amount of Baking Soda (ounces) per 10 ppm increase in TA and 0.1 increase in pH |
| 100 | 1.5 |
| 200 | 3 |
| 300 | 4.5 |
| 400 | 6 |
| 500 | 7.5 |
- Turn off the jets and heater of your hot tub and make sure the water is circulating.
- Add the required amount of baking soda to a bucket of warm water and stir well until dissolved.
- Pour the solution into your hot tub slowly and evenly around the edges.
- Wait for at least 15 minutes before turning on the jets and heater again.
- Test the pH and TA levels again after an hour and repeat the process if needed until you reach the desired range.
How to Prevent Low pH in Hot Tub Water?
The best way to prevent low pH in your hot tub water is to test and adjust the water chemistry regularly, at least once a week, or more often if you use your hot tub frequently. You should also follow these tips to keep your water balanced and healthy:
- Use a high-quality sanitizer that is compatible with your hot tub system and follow the manufacturer’s instructions on how much and how often to add it.
- Shock your hot tub water once a week or after heavy use to eliminate organic contaminants that can lower the pH level.
- Use a pH stabilizer or buffer that helps maintain a consistent pH level in your hot tub water.
- Use a hot tub cover to prevent rainwater, debris, and evaporation from affecting your water chemistry.
- Drain and refill your hot tub water every three to four months or as recommended by your manufacturer.
Conclusion
Keeping the pH level in your hot tub water within the ideal range is essential for the performance, longevity, and enjoyment of your hot tub. By testing and adjusting the pH level regularly, using soda ash or baking soda as needed, and following some simple maintenance tips, you can ensure that your hot tub water is always clean, safe, and comfortable.