How to Use Baking Soda to Raise Alkalinity in Your Hot Tub

In addition to the pH level, the alkalinity in the hot tub plays a important role in the water balance. Therefore, a low alkalinity should be corrected. But can you also use baking soda to raise the alkalinity in a hot tub, and how much do you need for it?

For every 100 gallons of water in the hot tub, add 1 tablespoon of baking soda. A hot tub with a capacity of 300 gallons of water, add 3 tablespoons of baking soda. Allow the baking powder to circulate and dissolve for at least 6 hours after adding it in the hot tub.

In this article, I’ll explain how to use baking powder in a hot tub to increase alkalinity, how much you need, and what to look out for.

What causes alkalinity to drop in a hot tub

To start with, a low alkalinity level in your hot tub can be caused by humans. 

People bring in tons of pollutants that might affect the water chemistry, and most hot tubs are also heavily used.

The pollutants might be anything from body oil and sweat to chemical residue from your bathing suit and even pee.

The refreshing qualities of a hot tub’s warm water may also contribute to the loss of alkalinity.

Mother Nature herself could be another cause.

Rainwater, which falls on the acidic side of the pH scale, is a typical culprit in reducing water alkalinity. If you don’t utilize a hot tub cover, your water may also become unbalanced after a rainstorm. 

Chlorine may also be the cause. Because chlorine tablets have a low pH level, using them in the tub can lower the alkalinity. 

Can you use baking soda instead of an alkalinity increaser?

Alkalinity can be increased in a hot tub in two ways: By utilizing alkalinity increaser products or by adding baking soda (sodium bicarbonate). 

Baking soda works just as well as an alkalinity increaser for boosting the alkalinity in your hot tub.

Furthermore, baking soda has the advantage of being both easily available and inexpensive.

Apart from that, there are a few more advantages of using baking soda to lower your hot tub’s alkalinity: 

  • Unlike some alkalinity increaser products, it never causes severe skin burns. 
  • It does not leak into the damaged storage areas. 
  • Unlike the harsh chemicals used to raise the hot tub’s alkalinity, it has no negative side effects. 

How to use baking soda to raise the alkalinity in a hot tub

Maintaining the proper alkalinity is crucial for the equipment that heats and circulates water in a hot tub.

To keep the pH in the neutral range of 7.2 to 7.8, harsh liquid or dry chemicals are typically utilized to raise and reduce it.

While adding these chemicals to the water, they might inflict serious burns to your skin, or they can leak and damage the space where they are stored.

On the other hand, a simple home remedy can boost pH levels without the hazards of harsh chemicals. 

Things you will need:

  • Test strips for the water test.
  • Bicarbonate soda (baking soda).
  • Measuring spoons.

Procedure: How to use baking soda to raise the alkalinity level

  1. Turn off the hot tub jets and use a water test strip to assess the pH level of the water. 
  2. For every 100 gallons of water in the hot tub, add 1 tablespoon of baking soda. For example, in a hot tub with a capacity of 400 gallons of water, add 4 tablespoons of baking soda. 
  3. Turn on the hot tub jets and let the water circulate for two to four hours, allowing the baking soda to dissolve.
  4. Recheck the water’s pH level. If the pH level is still below acceptable standards, turn off the hot tub jets and add more baking soda to the water. 
  5. Alternate between circulating the water and adding baking soda to the hot tub until the pH level is between 7.2 and 7.8. 

How much baking soda to raise alkalinity in a hot tub

For every 100 gallons of water in the hot tub, add 1 tablespoon of baking soda to raise alkalinity by 2 ppm.

For example, in a hot tub with a capacity of 400 gallons of water, add 4 tablespoons of baking soda.

But this is just an estimate.

You should keep testing the alkalinity level during hot tub usage.

When the water becomes murky, you need to immediately raise alkalinity in the hot tub.

How long does it take for baking soda to raise alkalinity?

How long it takes for the baking soda to increase alkalinity depends on how much you add and how strong your alkalinity is at the start.

If you’re adding baking soda into a hot tub that’s already got low alkalinity, adding baking soda can raise it to normal levels within 12 hours.

Allow the baking soda to circulate and dissolve for at least six hours after adding it.

During this period, keep the filtration system working.

Check the total alkalinity and pH levels with a liquid test kit or test strips.

Is it safe to use baking soda to raise alkalinity in a hot tub?

Baking soda is safe to use in a hot tub to raise alkalinity.

Baking soda can take up to a pound to substantially impact the pH, while other pH boosters require much less.

It’s important to note that the pH measures how acidic the water is, whereas alkalinity measures the water’s ability to neutralize the acid. 

Raising the pH in your hot tub with baking soda is an option. But, of course, you can use special remedies to raise the alkalinity in your hot tub.

Although baking soda can be used to slightly raise the pH of your hot tub’s water, it will only do so. 

Keep in mind that the pH level should be between 7.2 and 7.8 ppm.

Baking soda is mostly used to increase the alkalinity of your hot tub’s water, and if the pH level of your hot tub’s water is too high, it might harm parts of the hot tub’s equipment, such as the heater or pipes. 

Remember: You should first test the pH level of your hot tub’s water before adding baking soda to raise the pH level.

Take a sample of the water and place a test strip in it to do so. Wait a few minutes before comparing the test strip’s color to the color guide. 

Low or high pH in your hot tub can raise your risk of being exposed to hazardous bacteria that can cause legionnaires disease or hot tub folliculitis. 

Negative effects of low alkalinity in hot tubs

Alkalinity in a hot tub must be greater than 80 ppm. If it doesn’t, the tub will begin to develop the following problems: 

  • Green tub: When the water in your hot tub turns green, you know you’ve got a problem on your hands. On the other hand, Algae cannot thrive in a neutrally balanced environment. Algal blooms are almost unavoidable when alkalinity (and consequently pH) declines. 
  • Corrosion: Despite the fact that most tubs are built of fiberglass, low alkalinity water can cause corrosion. This can happen on any metal surface in the tub and inside the equipment, such as the pump and filter. If they become degraded, they will certainly need to be replaced entirely, which can be rather costly. 
  • The pH level will fluctuate: The pH level will fluctuate drastically if there isn’t enough alkalinity in the water. You could be in an acidic tub one minute and an alkaline tub the next. This is also known as pH bounce, and it occurs when the pH buffer in the water is insufficient. 
  • Bathers are irritated: Bathers are irritated by low alkalinity water, which makes it acidic and irritates those in the tub. It won’t just irritate their eyes, skin, or nasal passages; it will literally irritate them. It can also induce respiratory difficulty in certain persons. 
  • Tub damage: When low alkalinity is present, staining, etching, deamination, and cracking are possible outcomes depending on the tub’s material. A vinyl cover can also be harmed over time, becoming stiff and brittle. 

Conclusion on using baking soda to raise the alkalinity in the hot tub 

Baking soda raises pH slightly while significantly boosting alkalinity.

There is no way to not raise both.

However, you can raise one more than the other depending on what you use. 

On the other hand, baking soda is better for raising the alkalinity of your hot tub rather than the pH increaser.

  • Use baking soda if your hot tub has a low total alkalinity and a decent pH level.
  • Use soda ash or magnesium oxide powder if your pH is low and your total alkalinity is high. 

If you want to boost the alkalinity of the water in your hot tub, use one tablespoon of baking soda per one hundred gallons of water (about 6 tablespoons for most regular-sized hot tubs).

Do you have any further questions, how to use baking soda to raise the alkalinity in your hot tub ?

Contact me at @contactswimfool on Twitter, Facebook, YouTube, or Pinterest – I’ll be happy to help.

Have fun balancing the alkalinity in your hot tub with baking soda!

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Hi. I'm Max Berg. I've been in the pool industry since 2015 and have always felt drawn to water. I'm the author behind swimfool.com, where I share my years of experience in pool maintenance and give helpful tips on keeping a swimming pool or hot tub clean. My tips reduce the costs of water treatment and protect the environment.

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