how much baking soda to raise alkalinity in hot tub

How Much Baking Soda To Raise Alkalinity In Hot Tub?

Determining the right amount of baking soda to raise alkalinity in a hot tub can be confusing, especially for those new to hot tub maintenance.

Using too much baking soda can lead to cloudy water or even damage your hot tub’s equipment. While using too little may not be effective in raising the alkalinity level.

In this blog post, I’ll explore how much baking soda you need to raise the alkalinity level properly in your hot tub. I’ll also discuss the benefits of maintaining proper alkalinity levels, the signs of imbalances, and how to remedy high or low alkalinity.

As a general rule, one tablespoon of baking soda should be added for every 100 gallons of water in your hot tub. If you have a 4 person hot tub that holds around 300 gallons of water, you should add 3 tablespoons of baking soda. Alternatively, you can use alkalinity increaser products to raise alkalinity levels.

How Does Baking Soda Help to Reduce Alkalinity in a Hot Tub?

We all know high alkalinity levels in a hot tub and baking soda can come in handy to bring it down. Although baking soda usually rises both pH and alkalinity levels, but applying the right amount makes an excellent job of decreasing alkalinity.

However, first, you should understand why the alkalinity is high. Baking soda is commonly used to raise alkalinity levels so it may have been overused or added in excess.

To reduce alkalinity, you can add a pH decreaser or soda ash to balance the water back to an appropriate pH level. If you use baking soda instead, test the pH levels before and after adding it.

SpaGuard pH Decreaser

Bring balance back to your spa with SpaGuard pH Decreaser! This powerful formula from BioGuard is specially designed to lower the pH levels in your spa, so you can enjoy crystal clear water that’s gentle on your skin.

Remember, only add a small amount and use a pH increase to balance the pH levels.

General Guideline for Baking Soda Measurement to Raise Alkalinity in Hot Tub

Baking soda is always a fantastic alternative to harsh and expensive chemicals. But, measuring the right amount is essential to avoid costly repair and maintenance down the line.

Baking Soda
Baking Soda

As a general guideline, adding 1.5 pounds of baking soda for every 100 gallons of water is recommended to increase alkalinity by ten parts per million (ppm).

So for instance, if your hot tub holds 500 gallons of water and your current alkalinity level is at 70 ppm, you’ll need to add 7.5 pounds of baking soda to raise it to 100 ppm.

You should add baking soda in small increments, diluting it with water first and giving it ample time (around four hours) to dissolve before retesting alkalinity levels.

Remember to use a testing kit to monitor alkalinity regularly, and never add more than the recommended amount of baking soda.

With these straightforward guidelines, you can effectively raise your hot tub’s alkalinity with baking soda and safely enjoy its benefits.

Alternative Baking Soda Measurements Suggested by Experts to Raise Alkalinity for a Hot Tub

To raise the alkalinity properly of your hot tub, experts suggest alternative baking soda measurements that you may find helpful. The standard recommendation is to add one pound of baking soda per 10,000 gallons of water, to raise the alkalinity by 10 ppm (parts per million).

Some experts suggest a more precise approach to take the tub’s unique volume and current alkalinity level.

Also, one alternative method includes adding one-third of a pound of baking soda per 100 gallons of water to raise the alkalinity by 10 ppm.

Another option is to add one tablespoon of baking soda per 100 gallons of water to raise the alkalinity by one ppm. You can use a test strip to check your tub’s alkalinity levels and adjust accordingly for a more accurate measurement.

You should maintain alkalinity levels between 80-120 ppm for optimal water balance, providing a comfortable and safe hot tub experience.

On the other hand, overuse of baking soda can lead to high alkalinity levels and cause scaling or cloudiness in your tub. By measuring your baking soda additions accurately, you can ensure the alkalinity levels are right where they should be, providing a relaxing and enjoyable soak in your hot tub.

Baking Soda for pH Level Adjustment

Now we know that adding the right amount of baking soda to your pool or hot tub water can raise its pH level and alkalinity. So that ultimately results in clean, clear, and sparkling water that’s pleasant to bath.

baking soda for pH level adjustment

Moreover, baking soda’s natural buffering ability ensures that it’s a safe and natural way to keep stable pH levels in pools. You can also use baking soda to decrease algae buildup, reduce corrosion, and more.

If you want to add baking soda to your hot tub, simply make a 0.1% bicarbonate solution by mixing 0.5 grams of baking soda with 2 cups (500 mL) water and a few drops of liquid dish soap.

Adding baking soda to your pool/hot tub water can help you maintain appropriate pH levels effectively and inexpensively!

Additional Tip for Low pH Levels in Hot Tub

Having low pH levels in your hot tub can be frustrating. Sometimes it can also harm your skin and irritate your eyes. But don’t worry; there are additional tips you can follow to maintain your hot tub’s pH levels.

Here are some of them:

  • Use baking soda – Adding a cup of baking soda to your hot tub can increase pH levels.
  • Aerate your water – If your hot tub has a water feature, let it run to increase aeration, which can also raise pH levels.
  • Test your total alkalinity – Low alkalinity levels can cause pH levels to drop. Use a testing kit to determine the total alkalinity of your hot tub’s water and adjust it accordingly.
  • Don’t add too much shock – High levels of shock can lower pH levels. So, follow the manufacturer’s instructions when adding shock to your hot tub.
  • Avoid using oils or lotions – These products can lower pH levels, so avoiding them before entering the hot tub is better.

Remember to check your pH levels at least twice weekly and maintain your hot tub’s chemical balance regularly.

General Rules for Specific Hot Tub Sizes to Apply Baking Soda to Raise Alkalinity for a Hot Tub

When maintaining your hot tub, you should think is the alkalinity level. As mentioned, the alkalinity level should be between 80-120 parts per million (ppm). If the level is lower than that, you can use baking soda to raise the alkalinity.

hot tub sizes

The amount of baking soda needed will vary depending on the size of your hot tub.

  1. For a small hot tub (up to 150 gallons), add 1 tablespoon of baking soda for every 50 gallons of water.
  2. For a medium-sized hot tub (up to 400 gallons), add 1/4 cup of baking soda for every 100 gallons of water.
  3. For large hot tubs (up to 700 gallons), add 1/2 cup of baking soda for every 100 gallons of water.

You should only add baking soda when your hot tub is unused. You can also allow it to dissolve before testing the alkalinity level again.

You can read How Many Gallons in a Hot Tub? (Easy Formula)

Most Common and Silent Bad Effects of Using Baking Soda in Hot Tubs

Irregular and excessive use of baking soda can have silent bad effects on your hot tub.

Here are a few things you should be cautious about:

1. Corrosion – Baking soda, being alkaline, can lead to corrosion of various metal parts of your hot tub, including the heating element, pump seals, and even the bathtub’s interior. This can be dangerous and cause irreparable damage.

2. Foaming – Adding excessive baking soda to your hot tub can cause foam formation. The foam can build up, leading to a cloudy hot tub that isn’t just aesthetically unpleasant but also can clog your filters.

foam in hot tub

3. pH Imbalance – You can use baking soda commonly to raise alkalinity levels, but unregulated usage can cause an imbalance in pH levels. That’s why it can cause skin irritation and even respiratory issues. So try to measure pH levels regularly to avoid any discomfort.

4. Hard Water – Many regions already have issues with hard water. It is exacerbated due to the use of baking soda. Water hardness occurs when too much calcium or magnesium is in the water, resulting in limescale formation, which can negatively impact your hot tub’s longevity.

5. Chemical reaction – When baking soda is poured into hot water, a chemical reaction occurs, with sodium being released that might impact the calcium levels. This can lead to a decrease in calcium levels that are essential for ensuring the hot tub’s proper functioning.

Also, you can use baking soda in moderation and in line with measurements to avoid unnecessary damage to your hot tub. A better alternative would be to use specific hot tub chemicals to save money and resources while keeping your tub clean and efficiently maintained.

Rule of Thumb for Hot Tub Alkalinity Adjustment

As a hot tub lover with years of experience, I know that maintaining proper alkalinity levels is essential for crystal-clear water and a relaxing hot tub experience.

The rule of thumb for hot tub alkalinity adjustment is to add a pH decreaser to lower the pH. To ensure the best results, turn on the jets and pumps with blowers and air dials turned off before adding any chemicals.

This will help to distribute the chemicals evenly throughout the water. Remember that total alkalinity acts as a buffer against sudden changes in pH.

Therefore, maintaining proper alkalinity levels is crucial for a stable pH reading.

Following this simple rule of thumb, you can achieve perfectly balanced hot tub water and enjoy a relaxing and rejuvenating soak.


I hope this guide has helped answer your questions on how much baking soda to add to raise alkalinity in your hot tub. Remember to always test your water and consult your hot tub manufacturer’s recommendations for specific instructions.

Have any other hot tub maintenance questions? Leave them in the comments below, and I’ll do my best to help!


Hi, I'm Shimul, the founder of Pooltub Life. I'm excited about sharing the latest outdoor living trends with you. My goal is to provide you with up-to-date information that will help make your POOL & HOT TUB stylish and enjoyable. Read About Me More । Follow on Facebook

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