The Ultimate Guide: How to Lower Alkalinity in Hot Tub

Get ready for a hot tub revolution! High alkalinity levels can ruin your hot tub experience, but it doesn’t have to be that way. In this blog, we’ll share some simple and practical tips that will help you easily lower alkalinity in hot tub and enjoy a relaxing soak in no time. Whether you’re new to hot tubs or a seasoned pro, these tricks will make maintaining your hot tub a breeze. So, don’t let high alkalinity levels dampen your hot tub experience, join us on this journey and say hello to crystal-clear water and a perfect hot tub experience.

Table of Contents

What Does Alkalinity Mean in Terms of Water?

In hot tub water, alkalinity refers to the total concentration of alkaline substances in the water. Alkaline substances, also known as bases, are chemicals with a pH greater than 7. Alkalinity is important in hot tub water because it helps stabilize the water’s pH, which can prevent the pH from becoming too low or too high.

The ideal range for alkalinity in hot tub water is 80-120 ppm (parts per million). If the alkalinity is too low, the pH of the water may become unstable, which can lead to corrosion and other problems. If the alkalinity is excessive, it might cause the pH to become excessively high, which can also cause issues.

Is High Alkalinity in Hot Tub Dangerous?

High alkalinity in a hot tub can be dangerous if not properly managed. Alkalinity refers to the measure of the water’s ability to resist changes in pH levels, and the ideal range is between 80-120 ppm. When the alkalinity level is too high, it can cause several issues, such as cloudy water and scaling on the hot tub’s interior and equipment. The water can become cloudy due to the presence of high levels of dissolved minerals, particularly calcium and magnesium. High alkalinity levels can also make it difficult to balance the pH levels in the hot tub. Increased pH can lead to skin irritation and eye irritation for hot tub users.

How Water Hardness and Calcium Levels Affect Alkalinity Balance

Water hardness and calcium levels play a significant role in alkalinity balance in hot tubs. Hard water contains a high level of dissolved minerals, particularly calcium and magnesium, which can contribute to high alkalinity levels. The buildup of mineral deposits from hard water can damage a hot tub’s interior and equipment and require frequent maintenance. Excess calcium can cause your water to become cloudy and make it difficult to maintain balance. Hard water makes it challenging to maintain alkalinity levels.

How to Test for Alkalinity in Your Hot Tub?

There are a couple of reliable methods for testing the alkalinity in your hot tub. Each method has its advantages, so let’s explore both options:

1. Test Strips

Image: Canva

Test strips are a quick and straightforward way to get an approximate reading of your hot tub’s alkalinity level.


  1. Dip a test strip into the hot tub water for a few seconds, then remove it.

  2. Hold the strip horizontally to let excess water drain off.

  3. Compare the resulting color on the test strip to the provided chart on the package.

  4. Match the color to the corresponding alkalinity level to determine the approximate value.

  5. Record the alkalinity reading for future reference.


  • Simple and easy to use.
  • Provides a quick estimate of alkalinity.
  • No need for additional equipment.


  • May not be as precise as other methods.

2. Digital Test Kit

Lower Alkalinity in Hot Tub
Image canva

For more accurate and specific alkalinity readings, a digital test kit is the way to go.


  1. Collect a small sample of hot tub water using the test kit’s sampling tool.

  2. Insert the sample into the designated slot on the digital test kit.

  3. Wait for the device to analyze the sample and display the alkalinity reading on the digital screen.

  4. Take note of the precise alkalinity value for future reference.


  • Provides precise and reliable alkalinity readings.
  • No color matching required, reducing potential errors.
  • Suitable for those who prefer precise water chemistry control.


  • May be more expensive than test strips.
  • Requires occasional battery replacements.

Testing Tips

To ensure accurate and consistent results, consider the following tips:

  1. Take Multiple Samples: Collect water samples from different areas of your hot tub to account for any variations in water chemistry.

  2. Test Regularly: Make a habit of testing your hot tub’s alkalinity regularly, especially after adding chemicals to the water. Frequent testing helps maintain the desired range.

Lower Alkalinity in Hot Tub
Image: Freepik

What Are the Main Causes of High Alkalinity in Hot Tub Water?

Several factors can cause high alkalinity in hot tub water:

Use of high pH or alkaline chemicals:

If you are using chemicals that are designed to raise the pH or alkalinity of your hot tub water, it can cause the alkalinity to become too high.

Overuse of pH increasers:

If you are using pH increasers too frequently, it can cause the alkalinity to become too high.

Poor water balance:

If the pH, total alkalinity, and calcium hardness levels in your hot tub water are not properly balanced, it can cause the alkalinity to become too high.


If foreign substances such as soap, shampoo, or other contaminants are introduced into the hot tub water, it can cause the alkalinity to become too high.


If your hot tub is leaking, it can cause the alkalinity to become too high as fresh water is introduced into the tub.

Water sources:

Water quality of sources like hard water living area. Water quality is an important factor to consider when living in an area with hard water. Hard water is defined as water that has a high mineral content, usually containing calcium and magnesium.

What Happens If Hot Tub's Alkalinity Levels Are Too High?

High alkalinity also causes green water, which reduces the efficiency of sanitizers like chlorine and bromine. When the pH levels in your hot tub water are too high, calcium can build up, making the water look cloudy and leading to the formation of scale, which irritates the skin. Also, the water will have an unpleasant odor and flavor. A higher pH also is associated with an increase in biofilm formation.

What Is the Best Way to Lower the Alkalinity in A Hot Tub?

One of the best ways to lower the alkalinity in a hot tub is by using a pH decreaser such as sodium bisulfate or muriatic acid. These chemicals work by neutralizing the excess alkalinity in the water, bringing the alkaline level down to the ideal range of 80-120 ppm. And can be added to your hot tub water according to the instructions on the product label. To use a pH decreaser, follow these steps:

    1. Test the alkalinity of your hot tub water using a water testing kit to determine how much pH reducer you need to add.
    2. Turn off the circulation pump and heater for your hot tub.
    3. Add the recommended amount of pH reducer to your hot tub, following the instructions on the product label.
    4. Turn on the circulation pump and heater, then run the hot tub for at least an hour so the pH reducer can disperse evenly in the water.
    5. Test the alkalinity again to ensure that it is within the ideal range. If the alkalinity remains too high, you may need to apply an extra pH reducer.

It’s important to note that adjusting the pH and alkalinity of your hot tub water can be a delicate process, and it’s best to follow the instructions on the product label and test the water frequently to ensure that the levels are within the ideal range.

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Are There Any Natural Ways to Lower Alkalinity in Hot Tub?

There are a few natural ways to decrease the alkalinity in a hot tub, but it is important to note that these methods may not be as effective as using pH decreasers such as muriatic acid or sodium bisulfate.

One method is by using ascorbic acid, also known as vitamin C, which can help to lower the alkalinity levels in the water. Another option is to use citric acid, which can also help to lower the alkalinity levels.

Another natural method is to add phosphoric acid to the water, which is a natural acid found in many foods and beverages. It can also be used to decrease the alkalinity levels in hot tubs.

Overuse of these natural methods can also cause an increase in pH levels, which can be harmful to the hot tub equipment and the people using it. It’s also important to be careful when handling any chemicals, including natural ones, and to follow the instructions carefully to avoid any potential hazards.

Lower Alkalinity in Hot Tub

Tips for Keeping Your Hot Tub's Alkalinity Low

  • Testing your hot tub’s alkalinity routinely will alert you to any increases, enabling you to take action before the levels become too high.
  • Use a pH balancer to maintain the pH level of the water in your hot tub to prevent an increase in alkalinity.
  • By draining and refilling your hot tub, you can help reduce the alkalinity in the water.
  • A water softener can help to remove hard minerals from your hot tub water, which can contribute to high alkalinity levels.
  • Properly balancing the chemicals in the hot tub, such as pH, total alkalinity, and chlorine can help to prevent high alkalinity levels.
  • Properly maintaining the hot tub equipment, such as filters and jets, can help to prevent high alkalinity levels.
  • Monitoring the water evaporation and adding water when necessary, to prevent the increase of alkalinity levels.


In conclusion, it is important to maintain a healthy alkalinity level in your hot tub. Testing the alkalinity regularly and lowering it if needed is essential to ensure that your hot tub remains safe and enjoyable. With the right supplies and a few simple steps, you can quickly and easily lower the alkalinity in your hot tub to an optimal level.

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