How to Raise Alkalinity in Hot Tub

How to Raise Alkalinity in Hot Tub (or Lower)?

Have you ever noticed that your water is looking a little cloudy or discolored, or maybe it’s even irritating your skin? These could be signs that the alkalinity level of your water is out of balance.

But don’t worry—it’s easy to fix! In this article, I’ll explain everything you need to know about “how to raise alkalinity in hot tub or lowering the it so you can get back to enjoying your soak.

In this article, we’re diving into the nitty-gritty of hot tub alkalinity—how to raise it, lower it, and keep it stable so you can enjoy your hot tub without a care in the world. We’ll demystify the connection between pH and alkalinity, guide you through easy-to-follow steps for testing and adjusting levels, and even share some troubleshooting tips for those pesky, out-of-nowhere issues. So, grab your test strips, and let’s get your hot tub back to being the relaxing haven it’s meant to be!

What you’ll learn:

  • What alkalinity is and why it’s important for hot tub water
  • How to test alkalinity levels
  • How to raise alkalinity using baking soda
  • How to lower alkalinity using a pH reducer
  • Tips for maintaining ideal alkalinity levels
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How to Raise Alkalinity in Hot Tub Without Upsetting pH – step-by-step

To raise alkalinity without upsetting the pH in your hot tub, you can use sodium bicarbonate (baking soda). Baking soda is a mild alkaline substance that will raise the alkalinity level of the water without significantly affecting the pH level.

Here are the steps to raise alkalinity without upsetting pH in your hot tub using baking soda:

  1. Test the alkalinity level of your hot tub water. You can use test strips or a liquid test kit to test the water.
  2. Calculate the amount of baking soda you need to add. To do this, use the following formula:

Amount of baking soda to add (in pounds) = (Desired alkalinity level – current alkalinity level) * (Volume of hot tub water in gallons) / 10

  1. Dissolve the baking soda in a bucket of hot tub water.
  2. Add the baking soda solution to the hot tub and stir well.
  3. Allow the hot tub water to circulate for at least 30 minutes before retesting the alkalinity level.

If the alkalinity level is still not within the ideal range, you can add more baking soda in small increments until the desired alkalinity level is reached.

Here are some additional tips for raising alkalinity without upsetting pH:

  • Add the baking soda solution slowly to the hot tub water and stir well after each addition. This will help to prevent the pH level from fluctuating too much.
  • Allow the hot tub water to circulate for at least 30 minutes before retesting the alkalinity level. This will give the baking soda time to dissolve and distribute evenly throughout the water.
  • If you are unsure of how much baking soda to add, or if you have any concerns about raising alkalinity without upsetting pH, consult with a qualified hot tub professional. 

List of Some Popular Alkalinity Increaser

SpaChoice 472-3-4021 Alkalinity Increaser


The SpaChoice 472-3-4021 Alkalinity Increaser is designed to quickly and effectively raise the total alkalinity in your hot tub, ensuring balanced water chemistry. This product helps prevent pH fluctuations, protecting both your hot tub equipment and your skin for a more comfortable soaking experience.

Arm and Hammer Baking Soda - Increaser



Arm & Hammer Baking Soda is a versatile household staple known for its purity and effectiveness. It’s ideal for baking, cleaning, deodorizing, and even maintaining balanced alkalinity in your hot tub.

SpaGuard Spa Total Alkalinity Increaser


SpaGuard pH Increaser is a premium product designed to raise the pH levels in your hot tub safely and efficiently. Maintaining optimal pH balance helps protect your hot tub equipment and enhances your soaking comfort.

When choosing an alkalinity increaser for your hot tub, be sure to select a product that is compatible with the type of sanitizer you use. You should also consider the size of your hot tub and the desired alkalinity level when choosing a product.

It is important to note that alkalinity increasers should be used according to the manufacturer’s instructions. Adding too much alkalinity increaser can raise the alkalinity level too high, which can cause problems with the pH level of the water and can also damage the hot tub equipment.

Lowering Alkalinity Without Upsetting pH – step-by-step

You can use a pH reducer to lower alkalinity without upsetting the pH in your hot tub. A pH reducer is an acidic substance that lowers the alkalinity level of the water without significantly affecting the pH level.

Here are the steps to lower alkalinity without upsetting pH in your hot tub using a pH reducer:

  1. Test the alkalinity level of your hot tub water. You can use test strips or a liquid test kit to test the water.
  2. Follow the instructions on the pH reducer label to determine how much product to add.
  3. Add the pH reducer to the hot tub water slowly and stir well after each addition.
  4. Allow the hot tub water to circulate for at least 30 minutes before retesting the alkalinity level.

If the alkalinity level is still not within the ideal range, you can add more pH reducer in small increments until the desired alkalinity level is reached.

Here are some additional tips for lowering alkalinity without upsetting pH:

  • Add the pH reducer solution slowly to the hot tub water and stir well after each addition. This will help to prevent the pH level from fluctuating too much.
  • Allow the hot tub water to circulate for at least 30 minutes before retesting the alkalinity level. This will allow the pH reducer to dissolve and distribute evenly throughout the water.
  • If you are unsure of how much pH reducer to add or have any concerns about lowering alkalinity without upsetting pH, consult a qualified hot tub professional.

By following these steps, you can lower the alkalinity level of your hot tub water without significantly affecting the pH level. This will help to protect your equipment, keep the water clear and comfortable, and reduce the risk of skin irritation.

Here are some additional safety guidelines to keep in mind when lowering alkalinity in your hot tub:

  • Always wear eye protection and gloves when handling pH reducers.
  • Add the pH reducer to the hot tub water slowly and stir well after each addition.
  • Avoid splashing the pH reducer on your skin or clothing.
  • If the pH reducer gets on your skin or clothing, wash the affected area immediately with soap and water.
  • If you have any questions or concerns about lowering alkalinity in your hot tub, consult a qualified professional.

List of Some Popular Alkalinity Decreaser

Clorox Pool&Spa Spa pH Down


Clorox® Pool&Spa™ Spa pH Down is specifically formulated to reduce pH levels in your spa, ensuring balanced water chemistry for optimal comfort. This easy-to-use product helps prevent scaling and cloudy water, protecting your spa and skin.

Clorox Pool&Spa Swimming Pool pH Down


Clorox® Pool&Spa™ Swimming Pool pH Down is designed to safely lower the pH levels in your swimming pool, ensuring balanced and clear water. This product helps prevent scaling and cloudy water, making pool maintenance easy and effective.

SpaGuard pH Decreaser


SpaGuard pH Decreaser effectively lowers the pH levels in your hot tub, ensuring the water remains balanced and comfortable. This easy-to-use product helps prevent scale formation and protects your hot tub equipment from damage.

When choosing an alkalinity decreaser for your hot tub, be sure to select a product that is compatible with the type of sanitizer you use. You should also consider the size of your hot tub and the desired alkalinity level when choosing a product.

It is important to note that alkalinity decreasers should be used according to the manufacturer’s instructions. Adding too much alkalinity decreaser can lower the alkalinity level too low, which can cause problems with the pH level of the water and can also damage the hot tub equipment.

If you have any questions or concerns about choosing or using an alkalinity decreaser for your hot tub, be sure to consult with a qualified hot tub professional.

Hot Tub Alkalinity – What is Alkalinity and What is Hot Alkalinity?

What is Alkalinity?

Alkalinity is a measure of water’s ability to neutralize acids. It is caused by the presence of alkaline substances in the water, such as carbonates, bicarbonates, and hydroxides. Alkalinity is measured in parts per million (ppm).

What is Hot Tub Alkalinity?

Hot tub alkalinity is the water’s alkalinity level in a hot tub. Maintaining a balanced alkalinity level in your hot tub is important to protect the equipment and ensure that the water is comfortable and safe to soak in.

Why is Hot Tub Alkalinity Important?

Hot tub alkalinity is important for a number of reasons:

  • It helps to stabilize the pH level of the water. The pH level is a measure of how acidic or basic the water is. A balanced pH level is important for the comfort and safety of the bathers and for the proper functioning of the hot tub equipment.
  • It helps to prevent corrosion of the hot tub equipment. High alkalinity can cause scale to form on the equipment, which can reduce its lifespan and efficiency.
  • It helps to keep the water clear. Low alkalinity can cause the water to become cloudy and discolored.
  • It helps to improve the effectiveness of the sanitizer. The sanitizer used in hot tubs to kill bacteria and other microorganisms works best when alkalinity is within the ideal range.

Specific problems that can occur with low or high hot tub alkalinity:

  • Low alkalinity:
    • Rapid fluctuations in pH
    • Corrosion of metal parts
    • Etching and staining of surfaces
    • Cloudy and discolored water
    • Algae growth
  • High alkalinity:
    • Scale formation on equipment
    • Reduced effectiveness of sanitizer
    • Cloudy and discolored water

Therefore, it is important to maintain a balanced alkalinity level in your hot tub to protect the equipment, ensure the water is comfortable and safe to soak in and keep the water clear and clean.

Ideal Alkalinity Level

The ideal alkalinity level for a hot tub is between 80 and 120 parts per million (ppm). This range helps to ensure that the pH level of the water is stable, that the hot tub equipment is protected from corrosion, and that the water is clear and comfortable to soak in.

If the alkalinity level is too low, the pH level of the water can fluctuate wildly, which can cause corrosion of the hot tub equipment and make the water cloudy and discolored. If the alkalinity level is too high, scale can form on the equipment, which can reduce its lifespan and efficiency.

It is important to test the alkalinity level of your hot tub water regularly, at least once a week. You can use test strips or a liquid test kit to test the water. If the alkalinity level is not within the ideal range, you can adjust it using baking soda to raise the level or a pH reducer to lower the level.

Simple Steps to Accurate Measurements – Alkalinity Testing

7-Way Pool Test Strips, 100 Quick & Accurate Pool and Spa Test Strips

To get accurate alkalinity measurements, follow these simple steps:

  1. Gather your supplies. You will need a test kit that includes an alkalinity test. Liquid test kits are generally more accurate than test strips.
  2. Collect a water sample. Fill a clean container with hot tub water. The container should be large enough to hold enough water for all of the tests you will be performing.
  3. Read the test kit instructions carefully. Each test kit is different, so it is important to read the instructions carefully before testing the water.
  4. Perform the alkalinity test. Follow the instructions on your test kit to perform the alkalinity test. Be sure to time the test accurately.
  5. Read the results. Once the test is complete, compare the water sample to the color chart provided with your test kit. The color chart will tell you the alkalinity level of the water.
  6. Frequency of testing: Ideally, aim to check your hot tub’s alkalinity at least once a week if it’s frequently used, and every time before you add any chemicals. More frequent checks are in order if you’ve recently had a lot of guests or just refilled your hot tub.

Here are some additional tips for getting accurate alkalinity measurements:

  • Use a clean container to collect the water sample.
  • Make sure the water sample is representative of the overall hot tub water.
  • Perform the test in a well-lit area.
  • Be careful not to contaminate the water sample with your fingers.
  • Rinse the test container and any other equipment used in clean water after testing.

If you are not sure how to interpret the results of your alkalinity test, or if you have any questions about maintaining the alkalinity level in your hot tub, consult with a qualified hot tub professional.

Why is Alkalinity Low or High?

There are a number of reasons why alkalinity can be low or high in a hot tub.

Why is Alkalinity Low?

  1. Fresh Refill: When you’ve just filled your hot tub with fresh water, alkalinity levels can often start off on the low side.
  2. Rainwater: If your hot tub is outdoors and uncovered, rainwater can dilute the chemicals and lower alkalinity.
  3. Chemical Imbalance: Sometimes, using certain chemicals can throw off your alkalinity. pH decreasers, for example, often lower alkalinity as well.
  4. Heavy Use: The more people you have using your hot tub, the quicker your chemicals dissipate, potentially lowering alkalinity.
  5. Environmental Factors: Things like leaves, bugs, or dirt that get into the water can also affect your chemical balance, often lowering alkalinity.
  6. Low-Quality Chemicals: Cheaper, lower-quality chemicals can be less stable, causing fluctuations in your alkalinity levels.

Why is Alkalinity High?

  1. Too Much Alkaline Additive: It might sound obvious, but if you’re a little heavy-handed with alkalinity increasers, you could end up with higher levels than you wanted.
  2. High pH Levels: Alkalinity and pH levels are closely related. If your pH is high, often your alkalinity will be too.
  3. Improper Circulation: Poor water circulation can cause chemicals to be unevenly distributed, sometimes leading to pockets of high alkalinity.
  4. Contaminants: Things like oils, lotions, and detergents from bathers’ bodies can sometimes contribute to higher alkalinity levels.
  5. Tap Water: Depending on your location, your tap water could naturally have high alkalinity. Always test your water source before using it to fill your hot tub.
  6. Improper Testing: Believe it or not, sometimes it’s the test itself that’s off. Expired or contaminated test kits can give you incorrect readings.

Understanding why alkalinity levels swing one way or the other is the first step in taking control. Think of it as being a detective on your own hot tub case, looking for clues and figuring out whodunnit—or in this case, “what-dunnit” to your water balance. Once you know what’s causing the imbalance, you’re well on your way to solving the case and restoring harmony to your hot tub universe.

The Connection Between pH and Alkalinity

There is a strong connection between pH and alkalinity in hot tubs. pH is a measure of how acidic or basic water is, while alkalinity is a measure of water’s ability to neutralize acids.

The ideal pH level for hot tub water is between 7.2 and 7.8. If the pH level is too low, the water will be acidic and can cause corrosion of the hot tub equipment and irritation to the skin. If the pH level is too high, the water will be basic and can make the water cloudy and discolored.

Alkalinity helps to stabilize the pH level of hot tub water. When the alkalinity level is balanced, the pH level will be less likely to fluctuate.

If the alkalinity level is too low, the pH level can drop rapidly, which can lead to corrosion and skin irritation. If the alkalinity level is too high, the pH level can rise rapidly, which can make the water cloudy and discolored.

It is important to test the pH and alkalinity level of hot tub water regularly to ensure that they are within the ideal range. You can use test strips or a liquid test kit to test the water. If the pH or alkalinity level is not within the ideal range, you can adjust it using baking soda or a pH reducer.

Here are some tips for maintaining the ideal pH and alkalinity levels in your hot tub:

  • Test the pH and alkalinity levels of the water regularly.
  • Adjust the pH and alkalinity levels as needed using baking soda or a pH reducer.
  • Follow the instructions on the product label carefully when adjusting the pH and alkalinity levels.
  • Be sure to retest the pH and alkalinity levels after making any adjustments.
  • If you have any questions or concerns about maintaining the pH and alkalinity levels in your hot tub, consult with a qualified hot tub professional.

Here is a table that shows the relationship between pH and alkalinity:

WordPress Tables Plugin

By maintaining the ideal pH and alkalinity levels in your hot tub, you can protect your equipment, keep the water clear and comfortable, and reduce the risk of skin irritation.

 Risks Associated with High Alkalinity in Hot Tubs

High alkalinity in hot tubs can pose a number of risks, including:

  • Damage to hot tub equipment: High alkalinity can cause scale to form on hot tub equipment, such as pumps, heaters, and jets. This scale can reduce the efficiency of the equipment and shorten its lifespan.
  • Cloudy water: High alkalinity can make hot tub water cloudy and discolored. This can be unsightly and make the water less enjoyable to soak in.
  • Skin irritation: High alkalinity can irritate the skin, especially in people with sensitive skin. This can cause redness, itching, and burning.
  • Reduced effectiveness of sanitizer: High alkalinity can reduce the effectiveness of the sanitizer used to kill bacteria and other microorganisms in hot tub water. This can increase the risk of waterborne illnesses.

In addition to these risks, high alkalinity can also make it more difficult to maintain the ideal pH level in a hot tub. The ideal pH level for a hot tub is between 7.2 and 7.8. If the pH level is too high or too low, it can irritate the skin and eyes, and can also damage the hot tub equipment.

It is important to test the alkalinity level of your hot tub water regularly to ensure that it is within the ideal range. You can use test strips or a liquid test kit to test the water. If the alkalinity level is too high, you can lower it using a pH reducer. 

Risks Associated with Low Alkalinity in Hot Tubs

Low alkalinity in hot tubs can pose a number of risks, including:

  • Rapid fluctuations in pH: Low alkalinity cannot buffer the water from changes in pH, which can lead to rapid fluctuations in pH levels. This can irritate the skin and eyes, and can also damage the hot tub equipment.
  • Corrosion of metal parts: Low alkalinity can cause metal parts in the hot tub, such as pumps, heaters, and jets, to corrode. This can reduce the lifespan of the equipment and make it more likely to fail.
  • Etching and staining of surfaces: Low alkalinity can etch and stain the surfaces of the hot tub, making it look unsightly and difficult to clean.
  • Cloudy and discolored water: Low alkalinity can cause the water in the hot tub to become cloudy and discolored. This can be unsightly and make the water less enjoyable to soak in.
  • Algae growth: Low alkalinity can create a favorable environment for algae growth. Algae can make the water cloudy and discolored and can also irritate the skin and eyes.

In addition to these risks, low alkalinity can also make it more difficult to maintain the ideal pH level in a hot tub. The ideal pH level for a hot tub is between 7.2 and 7.8. If the pH level is too high or too low, it can irritate the skin and eyes, and can also damage the hot tub equipment.

How Long Does It Take to Stabilize Levels?

The amount of time it takes for alkalinity levels to stabilize in a hot tub will vary depending on a number of factors, including:

  • The initial alkalinity level of the water
  • The amount of alkalinity increaser or decreaser added
  • The circulation of the water
  • The temperature of the water

Generally speaking, it can take anywhere from 30 minutes to several hours for alkalinity levels to stabilize after adding alkalinity increaser or decreaser. It is important to test the alkalinity level of the water regularly to ensure that it is within the ideal range.

Here are some tips for helping to stabilize alkalinity levels in your hot tub:

  • Add alkalinity increaser or decreaser slowly and stir well after each addition.
  • Allow the hot tub water to circulate for at least 30 minutes before retesting the alkalinity level.
  • If the alkalinity level is not within the ideal range after 30 minutes, you can add more alkalinity increaser or decreaser in small increments until the desired alkalinity level is reached.
  • It is important to note that the temperature of the water can also affect the alkalinity level. Higher water temperatures can cause the alkalinity level to decrease. If you are having difficulty stabilizing the alkalinity level in your hot tub, try lowering the water temperature slightly.

If you have any questions or concerns about stabilizing alkalinity levels in your hot tub, be sure to consult with a qualified hot tub professional.

Important safety guidelines:

  • Always wear eye protection and gloves when handling alkalinity increasers and decreasers.
  • Add alkalinity increaser or decreaser slowly and stir well after each addition.
  • Avoid splashing the alkalinity increaser or decreaser on your skin or clothing.
  • If the alkalinity increaser or decreaser gets on your skin or clothing, wash the affected area immediately with soap and water.
  • If you have any questions or concerns about using alkalinity increasers or decreasers in your hot tub, be sure to consult with a qualified hot tub professional.

Final Thoughts

Alkalinity is an important factor in hot tub water chemistry. It helps to stabilize the pH level, prevent corrosion, and keep the water clear and comfortable. The ideal alkalinity level for a hot tub is between 80 and 120 ppm.

It is important to test the alkalinity level of your hot tub water regularly to ensure that it is within the ideal range. You can use test strips or a liquid test kit to test the water. If the alkalinity level is too low or too high, you can adjust it using baking soda or a pH reducer.

Be sure to follow the manufacturer’s instructions carefully when adding an alkalinity increaser or decreaser to your hot tub water. Adding too much can cause problems with the pH level of the water and can also damage the hot tub equipment.

If you have any questions or concerns about alkalinity in your hot tub, be sure to consult with a qualified hot tub professional.

Here are some final thoughts on alkalinity in hot tubs:

  • Alkalinity is an important factor in hot tub water chemistry.
  • The ideal alkalinity level for a hot tub is between 80 and 120 ppm.
  • It is important to test the alkalinity level of your hot tub water regularly.
  • You can adjust the alkalinity level using baking soda or a pH reducer.
  • Be sure to follow the manufacturer’s instructions carefully when adding alkalinity increaser or decreaser to your hot tub water.
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