Hot tubs require regular testing to maintain the right water chemistry. Two of the most critical factors a hot tub owner must closely monitor are water alkalinity and pH.
These elements affect the clarity and cleanness of your hot tub water. They also play an essential role in extending the life of your spa equipment, preventing skin irritation, and ensuring a worry-free, relaxing experience.
In this article, you’ll understand why testing hot tub pH and alkalinity is important and how to do it accurately. You’ll also learn more about the relationship between the two and the best practices for keeping your hot tub water balanced.
Hot Tub pH Levels
The pH of your hot tub water is a measure of how acidic or alkaline it is. It’s a number measured on a scale from 0 to 14. Usually, the levels in the middle (around 7) are considered balanced or neutral.
Ideally, you want to keep your hot tub water pH levels between 7.2 and 7.8, slightly over the midrange. When you keep your measurements within these numbers, your water remains safe and enjoyable to use (neither too acidic nor too basic).
What Can Imbalanced Water pH Levels Do?
Whether they’re too low or too high, imbalanced water pH levels may cause numerous issues for hot tub users. In fact, they can lead to consequences that affect the life of your spa equipment as well.
Here are a few concerns you can avoid by balancing your hot tub water pH levels:
- Skin and Eye Irritation: Low pH levels can cause redness, itching, and a burning sensation in the eye, while high levels may leave your skin feeling dry and tight.
- Corrosion: Acidic water can corrode the metal components of your hot tub, such as pumps, jets, etc.
- Scaling: Alkaline water, on the other hand, encourages mineral deposits to form. This results in scale buildup on the surface of your hot tub as well as the heaters and filters. Over time, this can affect water flow, heating efficiency, and equipment life span.
- Reduced Sanitizers Effectiveness: Low or high water pH levels can interfere with how sanitizers work and cause them to become less effective. As a result, you may experience a foul smell when lifting the cover of your hot tub.
- Cloudy Water: Both high and low pH levels disrupt water clarity, making your hot tub look gloomy. If you notice the water surface becoming a bit foamy, it’s a strong sign you need to adjust pH levels.
How To Test Hot Tub pH Levels
Testing your hot tub’s pH is a straightforward process. To keep your hot tub clean, fresh, and ready to use at all times, you need to test it at least once or twice a week (This mainly depends on how often you use it).
Here are three ways to test water pH levels in a hot tub:
- Test Strips: Hot tub test strips are quick and easy to use. All you need to do is dip a test strip into your hot tub water and observe it while it changes color to indicate the reading.
- Liquid Test Kits: These kits are slightly more accurate than test strips. Generally, they involve adding reagents to a water sample and comparing the results to a color chart.
- Digital Testing: A hot tub pH meter is a digital device that measures the water's pH levels. It provides instant and more accurate readings than other methods.
- Lab Testing: This is the most precise option, as it’s done with testers in a lab to provide the exact pH reading. For this method, you don’t always need to have a professional come over. Instead, you can send a sample of your water to a designated provider.
How To Alter pH Levels
If the pH in your hot tub water is out of range, you can use certain chemicals to make proper adjustments.
Lowering pH Levels
If the pH levels are above 7.8, here’s what you need to do:
- Add a pH decreaser (usually sodium bisulfate).
- Make sure to follow the manufacturer's dosage instructions, as adding too much can cause a drastic pH drop.
- Sprinkle the decreaser evenly over the surface of the water.
- Turn on the jets and keep them running for at least ten minutes to help distribute the decreaser.
- Re-test the water after 15 to 30 minutes and repeat the process when necessary (sometimes, you might need to allow the water to circulate for a few hours before re-testing).
Raising pH Levels
If the pH levels are below 7.2, you’ll need to increase this number. Check out how to do it:
- Add a pH increaser (at most times, sodium carbonate).
- Follow the proper dosage that may vary depending on the hot tub size and severity of the imbalance.
- Distribute the increaser evenly across the water with the jets on.
- Keep the jets running for a few minutes.
- Re-test and adjust if needed.
Hot Tub Alkalinity
Alkalinity is another key component of hot tub water chemistry, closely interconnected with pH. Principally, without balanced alkalinity, pH levels can fluctuate widely, leading to unstable water chemistry and other potential issues. So, you can think of it as a stabilizer for pH levels.
Ideal Water Alkalinity Levels
In general, alkalinity measures the concentration of alkaline in the water and is expressed in parts per million (ppm). The ideal range for total alkalinity in a hot tub should range from 80 to 120 ppm.
Keeping alkalinity within this range ensures balanced water chemistry, prevents fluctuations in pH, and protects your spa equipment.
What Imbalanced Water Alkalinity Can Do
Out-of-range alkalinity can cause a range of problems for the hot tub and its users alike. Here’s what can happen when it’s too high or too low:
- pH Instability: Quick and unpredictable pH fluctuation can be a result of an imbalance in alkalinity. Without stabilizing alkaline in water, it can be hard to bring pH back into the ideal range.
- Corrosion: Low alkalinity increases the risk of damage to the hot tub’s metal parts as well as its surface.
- Scaling: As mentioned above, high alkalinity in water encourages the formation of mineral deposits on hot tub surfaces and other essential parts.
- Discomfort: Skin irritation and eye discomfort are among the symptoms you may experience when your hot tub’s water is low in alkalinity.
- Cloudy Water: Excess alkalinity can cause murky water that requires additional cleaning and chemicals (due to algae growth).
How To Test Alkalinity in a Hot Tub
Testing alkalinity is just as easy as measuring other chemicals in your hot tub water. Ideally, it should be a part of your regular hot tub maintenance routine. Here’s how to get an accurate reading:
- Test Strips: Dip the test strip into your hot tub’s water and observe the color result before comparing it with the included chart.
- Liquid Test Kits: Add the included reagents to a water sample to measure alkalinity more accurately.
- Digital Testers: Just like the digital pH meter for hot tubs, these testers provide exact ppm readings for more precise adjustments.
How To Increase and Reduce Alkaline Levels
It’s crucial to maintain proper alkalinity levels between 80 and 120 ppm. Alkalinity has major effects on both water pH and quality in your hot tub. Here’s how to adjust it:
Increasing Alkalinity
Lower alkalinity is usually a result of using acidic chemicals like pH decreasers. It can also happen due to other factors like sweat, body oils, and hair products, which can disrupt water chemistry.
If you measure water alkalinity and it turns out to be below 80 ppm, do the following:
- Add an alkalinity increaser, which is a product that contains sodium bicarbonate.
- Refer to the manufacturer’s guidelines, and use the proper amount based on the size of your hot tub.
- Turn on the jet to distribute the chemicals evenly.
- Check the levels again and adjust further if needed.
Reducing Alkalinity
Even if you haven’t used too much of the alkalinity increaser, your hot tub might still measure high. This can be due to natural water hardness in the area you live in. Naturally, hard water contains high levels of calcium and magnesium, which raise the alkalinity.
Alkalinity and pH are closely related. So, when one rises, the other might increase as well. If your hot tub alkalinity measures over 120 ppm, follow these steps:
- Add a pH decreaser, which is a product that contains sodium bisulfate.
- Use small amounts gradually to avoid over-correction.
- Run the jets to encourage natural pH stabilization after adjustment.
- Monitor the alkalinity and repeat the process as needed.
Best Hot Tub Chemicals
To maintain clean, balanced, and safe hot tub water, you need to use the right chemicals. Here’s a brief list of the most important types of chemicals to purchase and their uses:
- Sanitizers: They help keep your hot tub water clean by killing bacteria and preventing algae growth. Chlorine and bromine are the most common options, with the latter being ideal for hot tubs because it remains effective at high temperatures.
- pH Adjusters: To control the water pH levels and keep them within range.
- Alkalinity Balancers: To adjust total alkalinity.
- Calcium Hardness Adjusters: To keep water hardness at bay.
- Other Chemicals: Including stain and scale removers, defoamers, chlorine shock, hot tub enzymes, water conditioners, etc.