Yes, Use Soda To Raise Hot Tub Alkalinity [1 tbs/100 gallons]

Raising your hot tub’s alkalinity is different than just making it more basic or less acidic. I will try to explain how to raise the total concentration of alkaloids within the water.

The most common types of alkaloids you can find in your hot tub water are carbonates, hydroxides, bicarbonates, and other minor alkaloids.

So how much baking soda do you need to raise alkalinity in hot tub? In order to raise your hot tub alkalinity, you should:

  1. Add 1 tbsp of baking soda to the hot tub for every 100 gallons of water it holds.
  2. Then turn on the hot tub jets and have the water circulate along with the baking soda for 2 to 4 hours.
  3. Keep switching between circulating and adding baking soda to the water until the pH level gets within the range of 7.2 to 7.8.

But first, if you are not aware of what these terms actually mean, let’s remind ourselves and try to answer more questions about alkalinity altogether. So, how do you increase alkalinity?

What Is Total Alkalinity And How It Is Different From pH Level

Before we go deeper into the topic, there is one thing we should really make clear. Your total alkalinity and pH, when put together, are actually two very different things. 

The regular tap water we know today is (opposite of acidic) called “alkaline”. There are often misconceptions about these terms that so often get people confused, even those in the industry. 

To put it simply, pH is a relative measure of a solution’s alkalinity as it relates to water. On the other hand, the term “total alkalinity” (TA) measures the total number of alkaloids within a solution’s sampled volume.

Now that we know that total alkalinity is different from pH levels, meaning that total alkalinity isn’t a relative measure, but a measure of all alkaline chemicals that are dissolved in a sample (such as water). Total alkalinity will usually represent the concentration of hydroxides, carbonates, bicarbonates, and other alkaloids within your sample (of water). 


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When it comes to measuring the two, total alkalinity is measured in a different way than pH ranges. Total alkalinity is actually measured in parts per million (ppm), which you could have come across in other posts, unlike the relative pH ratings. 

Having a higher concentration of alkaloids means that your hot tub’s pH will become more stable since it requires more of a given substance in order to change its concentration of alkaloids. Understanding these concepts, we can say that it is totally possible to have a hot tub’s water pH balanced while still having issues with alkalinity.

The alkalinity of the hot tub water protects the pH against sudden fluctuations. The ideal level should be between 80 – 160 mg/I. If the alkalinity drops below 80 mg/l, there could be considerable fluctuations in the pH value. This could result in corrosive water conditions, unnecessarily affecting your tub equipment.

In addition, the water may be perceived as unpleasant by the tub users. To increase alkalinity, add HTH Spa pH Stabilizer or Leisure Time Alkalinity Increaser.

If the alkalinity is too high, adjusting the pH is very difficult, if not impossible. High alkalinity can be reduced with pH Minus powder, which is poured into the water at the deepest part of the tub at once.

If both the pH and the total alkalinity need to be corrected, adjust the total alkalinity first.

How do I raise alkalinity without raising pH in the hot tub?

Pool owners have a great solution for this. It is called Borax (available in the laundry section) which is used in order to raise TA without affecting pH too much.  I would assume it would be the same in a spa.

  • Soda Ash (sodium carbonate, washing soda) raises both pH and TA fast
  • Baking soda (sodium bicarbonate) raises pH slightly and raises TA fast
  • Borax ( sodium borate, s. tetraborate, disodium tetraborate) raises pH while only slightly raising TA
  • Aerating after adding muriatic acid raises pH while lowering TA, how much it lowers the TA is dependent on what the pH is when you start airating.  

Generally, the lower the pH the more you will lower TA.

Laundry Soap Kit - Fels Naptha 4 bars, 20 Mule Team Borax Natural Laundry Booster, & Arm & Hammer Super Washing Soda
  • Arm & Hammer 55 Oz. Super Washing Soda Laundry Booster. Pack of 1.
  • Detergent booster and household cleaner.
  • Improves liquid laundry detergent performance up to 40%. 100% fragrance and phosphate-free. 55 oz.
  • 20 Mule-Teama 65 Oz. Borax Laundry Booster. Pack of 1.
  • Natural laundry booster. 20 Mule-Team Borax has a multitude of household uses to help families clean and deodorize their homes for over 100 years.

How Do I Test The Alkalinity In My Hot Tub

You certainly want to use the test strips. For those who don’t know, pH and total alkalinity test strips are a single test strip that just has two separate test pads, one for pH and the other for total alkalinity. 

pH Test Strips for Testing Alkaline and Acid Levels in The Body. Track & Monitor Your pH Level Using Saliva and Urine. Get Highly Accurate Results in Seconds.
  • Monitor Your Health – Take a look at your body from the inside out with saliva and urine pH test strips for humans. Your kit has 125 strips, a color test chart, and easy PDF instructions by Just Fitter.
  • Levels of Success – Wet your litmus paper pH test strips with urine or saliva mid-morning, wait 15 seconds, then compare to the chart. Both pads will change to reveal the most accurate .25 pH range.
  • Stay on Track – According to Nobel Prize winner Dr. Warburg, “Disease can’t survive in an alkaline body.” Use your alkaline strips test for humans multiple times daily to monitor your diet’s progress.
  • Uncompromised Accuracy – Seal your light-blocking bottle and store your pH strips for urine and saliva in a dry place. Do not use your strips to test blood, products, or pool water.
  • You’re Our Priority – Helping people is our top concern, but high-quality Just Fitter ph test strips are sensitive to heat and light. In the unlikely event they malfunction, contact us for an immediate replacement.

The test strips are a simple alternative to wet chemical tests since they will give reproducible results for each test separately. 

Look at the test ranges for each parameter:

pH6.0 – 9.0
Total Alkalinity0 – 360 ppm

How To Use The Test Strips

Follow the steps and tips below in order to get as accurate readings as possible

  1. You should dip one test strip into a water sample for 10 seconds and then remove it.
  2. Immediately match the pH test pad color
  3. Match the total alkalinity test pad color. 
  4. It’s a simple test with no chemicals to mix. Your results are obtained in 30 seconds
  5. The test strips are safe to use, with no hazardous chemicals

Is Low Alkalinity Bad In A Hot Tub

If your alkalinity level is too low, then your hot tub pH can fluctuate pretty badly even at the slightest addition of an acid or base. 

This can cause the pH to drop randomly, which then causes damage to the hot tub shell and metal surfaces, and it will be bad for all the users as well. 

Therefore, it is really important to run routine tests, and generally, it is recommended to take at least one test a week. 

As we said, low total alkalinity is also bad for your hot tub’s various components. The surface of the shell usually becomes etched, and pitted, having the protecting layer of the shell delaminated. 

Any metal parts that come into contact with water having low total alkalinity can cause corrosion, putting your heating elements, heaters, and pipes at risk. Additionally, it can cause calcium scaling, making it more difficult to keep surfaces clean and plumbing free of scale buildup.

Will Alkalinity Increaser Raise pH

Alkalinity increaser is sodium bicarbonate (which is also called sodium hydrogen carbonate). Its main job is to raise Total Alkalinity. Alkalinity increaser has a pH of only 8.3, which will increase overall pH levels, but only if they were extremely low. And this is the proper way how to raise alkalinity in the hot tub. However, when it comes to the general impact on pH, it will certainly have a lesser effect on overall pH.

Spa Essentials 32538000 Total Alkalinity Increaser Granules for Spas and Hot Tubs, 2-Pound
  • Raises alkalinity level to protect spa water from sudden changes in pH
  • Helps prevent staining, corrosion and pH bounce
  • Properly balanced spa water is a must if you want to fully enjoy your spa

What Causes Low Alkalinity In Hot Tub

If you would have two choose between the two extremes, low alkalinity is for sure the more serious of the two. It can cause quick fluctuations in pH, because then the water is not able to counteract the effects of acids, such as acid rain or naturally occurring minerals. 

Such an environment has a number of effects on the appearance of your spa: it can damage and erode its surfaces while corroding metal parts, and a perfect storm can lead to unattractive stains. Low alkaline water will also not be able to balance the amount of phosphate that algae feed on, resulting in green water.

Both MPS and Dichlor are net acidic after considering their consumption, so you will definitely have a TA drop in this situation over time (it’s just like adding acid to your spa) and need to add either baking soda or pH Up to bring it back to where it was.  The only thing that a certain TA value brings in this situation is relative pH stability.  

That is, at a certain TA level, the rate of pH increase due to carbon dioxide outgassing can be equal to the rate of pH decrease from the net acid sources of chlorine or oxidizing agent. 7 tablespoons MPS and 1 tablespoon dichlor (i.e. one week of chemical use) would require 2.6 tablespoons baking powder to compensate for the decrease in TA, provided that the carbon dioxide outgassing kept the pH constant.  

You need to add more because there is not enough carbon dioxide outgassing so that the pH decreases slightly.  At a higher TA level, you can achieve this pH balance, but you need to add something to restore the TA (carbonates lost as carbon dioxide). It is when you use a hypochlorite source of chlorine that the TA is fairly stable and where a lower TA to minimize carbon dioxide outgassing makes the pH more stable.

Should I Raise pH Or Alkalinity First

Your total alkalinity (TA) and pH will move together. The trick is to get your pH in line first, then raise total alkalinity a bit higher than you want it and SLOWLY lower the pH back down. 

This should get your total alkalinity where you want it to be. In addition, the constant aeration in a spa causes total alkalinity to go down because of the gassing off of CO2. 

This explanation is pretty technical but the solution is not that hard. And realize that you will possibly have to be adjusting total alkalinity at regular intervals. Keep track of your testing results and soon you will learn how high to raise the total alkalinity so it is in line once you adjust your pH back down.

How Much Baking Soda Does It Take To Increase Alkalinity

Researcher and author Dr. Robert O. Young has been researching the importance of pH balance for over two decades now. He has been looking for different ways to increase the alkaline levels by adding an alkaline ingredient to your water. 

So how much baking soda is needed to raise alkalinity in a hot tub according to Dr. Young? Dr. Young recommends simply adding half a teaspoon of baking soda to a gallon of water and mixing it vigorously to ensure it mixes in completely. Since baking soda is highly alkaline, adding only a small amount to your purified water will result in a gallon of alkaline water.

Depending on how much water can your hot tub hold, you can easily calculate the amount of baking soda you will need.

It is important to state that you should continue to test your pH levels as you are adding soda and mixing your water.

Is It Safe To Bath With Low Alkalinity

The term pH means the “power of hydrogen,” and it’s measured on a scale that goes from 0 to 14. When you measure your pH level and it shows that it is higher than 7, which is neutral, then the water is alkaline. That means it has an excess of negative hydroxide ions. 

In case your water test shows a pH level below 7, then that means that the water is acidic, meaning it has a surplus of positive hydrogen ions. 


Have You Considered Switching From
Chlorine To Bromine?

There’s been a trend where people are switching from chlorine to bromine. I feel there is not a lot of information about that transition and how to go about it since you can’t mix the two. I have addressed the most common misconceptions about this in the following article.

The pH scale is logarithmic, so hot tub water with a pH of 6 is 10 times more acidic than water with a pH of 7. Following the math, hot tub water with a pH of 5 is a hundred times more acidic than the pH 7 one.

Now that I have explained the math, when the pH is low, meaning the water is acidic, swimmers could suffer from itchy skin, rashes, burning eyes, and dry hair. 

The hot tub and all its components can suffer, too, since acidic water can corrode shells, metal accessories, and machinery in the water circulation and purification system. 

In addition, free chlorine levels become unpredictable and extremely difficult to maintain in acidic water. Despite all of the above, it’s usually still safe to spend time in your hot tub. It just might not be as comfortable.

How Does Rain Affect Hot Tub Alkalinity

Rainwater is known to be acidic so it definitely doesn’t help with maintaining the proper pH level of your hot tub water. You should always cover your hot tub when raining.

When rainwater enters the hot tub, it can change your water’s pH, alkalinity, calcium hardness, total dissolved solids (TDS), and other chemical levels as well as bring contaminants (e.g. debris, dirt) into the hot tub. This will obviously depend on where your hot tub is placed and whether there is a chance for extra dirt to enter the hot tub  

Since rainwater is generally acidic, then your hot tub water can become corrosive and cause damage to the shell and metal parts of your hot tub. The extent of the chemistry issues you’ll experience will largely depend on how much rain pours in your hot tub. 

For example, light rain, should not really have any effect on your hot tub water. Although, you should always be certain that your hot tub water chemistry is properly balanced at all times.

Will High Alkalinity Make Hot Tub Cloudy

If you test your hot tub water for total alkalinity and it shows high levels of alkalinity, excess of carbonates can make the hot tub cloudy. High total alkalinity levels will also make it hard to control your pH level and keep it in check. 

You should use pH decreaser in order to lower total alkalinity to around 100 ppm. In case your hot tub pH level is outside of the range of 7.2 to 7.6, adjust accordingly for easier control of cloudy water.

Does Shocking Hot Tub Raise pH

You know that every once in a while, in order to clear your hot tub of any cloudiness and contaminants, you should shock your water. Let’s remind ourselves about the chemical normal levels that should be maintained in your hot tub at all times. Any of those that measure outside of the given range should be fixed.

Bromine3.0 5.0

Shocking your hot tub will certainly balance your pH levels and not raise it. Again, all of these chemicals are related and can cause one to raise another. Make sure you perform enough tests before jumping in the hot tub.

How much alkalinity to add to the hot tub

Hot tub alkalinity is an important aspect to consider because it determines how well your hot tub performs. Ideal hot tub alkalinity levels should range from 80 – 120 parts per million.

Before you decide to add any chemicals into the hot tub, you want to test the alkalinity. You may not immediately detect low alkalinity in a hot tub. Usually, a decrease in alkalinity will lower the pH levels of water in the spa.

Low alkalinity makes the water more acidic, which consequently irritates your eyes and skin. Besides, the acidity may also corrode the surfaces of the hot tub. You may also notice that you may have to use more sanitizers to keep the hot tub safe for use.

Alkalinity may also go higher than recommended. In this case, you may notice the water starting to turn cloudy. High alkalinity doesn’t have many adverse effects like low alkalinity.

When the alkaline levels in your hot tub water are high, you may have problems with clogged pipes and filters. Besides, the water pressure may increase due to clogging. You may also notice water scaling on the surfaces of the hot tub. 

Alkalinity increaser for hot tubs 

When we mention increasing the alkaline levels in the water, we don’t imply making it more basic or acidic. Instead, we focus on the concentration of alkaloids in the water. The level of alkaloid concentration is then determined by the number of carbonates, hydroxides, and bicarbonates.

Alkalinity increasers are products meant to raise the level of alkaloids in the water. Simply put, alkalinity increasers raise the ability of the water to resist drastic pH changes.

The best alkalinity increase is sodium bicarbonate (baking soda). Any product you buy to increase alkalinity in the hot tub, make sure it contains sodium bicarbonate. 

Best alkalinity increaser for hot tubs

Understandably, there are so many alkalinity increasers in the market. Getting the best for your hot tub may be daunting especially if you don’t know what to look for. Here is a guide on some of the best products.

1.  Hot Tub Things pH and Alkalinity Up

Hot Tub Things is a reputable brand in the hot tub market producing spare parts and other products. This alkalinity increaser comes with instructions that are easy to follow making it ideal for first time hot tub owners.

This product also works instantly and you don’t have to use too much to achieve the desired results. You, therefore, get value for your money which is what every hot tub owner wishes for.

Hot Tub Things pH and Alkalinity Up 2 Pounds - Protects Your Spa from Corrosion
  • Keep hot tub water in check -- this product increases pH and Alkalinity to obtain the proper balance!
  • America's #1 Trusted Brand of Hot Tub Chemicals
  • Safety Tested to Assure Quality, Guaranteed Performance
  • Formulated Exclusively for Hot Tubs And Made from the Purest Chemicals Available
  • Compare to Leisure Time Alkalinity Increaser


  • Works instantly
  • Easy to use
  • Quality product
  • Gives value for money


  • The bottle doesn’t have a tamper proof seal

2.  Spa Essentials 32538000 Total Alkalinity Increaser Granules

If you prefer alkalinity increasers made of granules over liquid ones, then this is your go to product. This Spa Essentials alkalinity increaser also helps to balance pH levels in the water while protecting the hot tub from corrosion.

Spa Essentials 32538000 Total Alkalinity Increaser Granules for Spas and Hot Tubs, 2-Pound
  • Raises alkalinity level to protect spa water from sudden changes in pH
  • Helps prevent staining, corrosion and pH bounce
  • Properly balanced spa water is a must if you want to fully enjoy your spa

If you’re worried about granules not dissolving as fast, you need not worry because the granules on this product dissolve very fast.


  • Granules dissolve fast
  • Quality product
  • Easy to use


  • Some clients complain of receiving half-filled bottles

Adding baking soda to hot tub

Maintaining the correct alkalinity in the hot tub is the best way to give it a long life. Baking soda is the most natural product that helps maintain alkalinity and pH levels in check.

When using baking soda in the spa, you need to determine the capacity the hot tub holds. As a general rule of thumb, you need to add 1 tablespoon of baking soda for every 100 gallons of water.

When you add baking soda into the water, it’s important to turn on the jets so that it can evenly distribute the baking soda in the water. It’s also advisable to keep testing the pH levels so that you ascertain the levels before adding any more baking soda. 

After adding baking soda into the hot tub, you need to give the water about 4 hours before you can use the hot tub. 

How to lower pH in hot tub

The PH in your water may be higher than required for different reasons. One of those reasons is if you add more ph increasers than required. You may also have high ph if the water in your area has a higher pH than normal.

PH decreasers work by increasing the concentration of hydrogen in the water thus lowering the pH.

Sodium bisulphate also known as dry acid is one of the most effective chemicals when you’re trying to lower the ph in the water. The other alternative pH decreaser is muriatic acid. The two chemicals are different and the usage of each differs.

For example, you need about 1.23 liters of muriatic acid for every 10,000 gallons of water. With this amount, you can expect to lower the pH by about 10 parts per million.

After adding a pH decreaser, allow the jets to run to allow for even circulation of the chemicals. Also allow the water about 3 – 6 hours before you can use it.

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Editorial Staff

I'm Adnan Sabanovic, the guy behind Hot Tubs Report. I've had a chance to enjoy hot tubs last few years and have really become interested in owning one of them. Nearly every weekend you'll find me spending time with my family or playing sports. If I am not doing that then I'm here writing about tubs on Hot Tubs Report. This blog is a research for my first hot tub which I decided to document and share publically so others can benefit from it as well.

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