How To Raise pH In A Hot Tub


Share This Post

There are two main ways to raise pH in a hot tub: using soda ash (sodium carbonate) or baking soda (sodium bicarbonate). 

Having a hot tub in your home is a luxury, however, sitting back and relaxing in your hot tub doesn’t come without cleaning and water quality maintenance. 

When owning or working with hot tubs, it is important that proper water cleaning and maintenance is carried out to ensure that the water chemistry is balanced and that it is safe for human use.

One of the issues with constantly running a hot tub is the decrease in pH water levels. Therefore, raising the pH is something that you should learn if you’re working with or owning a hot tub. 

In this article, we will cover why the pH of water is essential for hot tubs, the issues with low pH levels inside a hot tub, and how you can raise pH levels when they drop below the optimal pH level for hot tubs. 

Hot Tub Water pH 

Hot tubs are a body of water that need regular maintenance to ensure that the water remains fresh and healthy. It is also critical to monitor pH levels inside your hot tub to prevent health issues for yourself and other hot tub bathers.

The pH scale measures how acidic or alkaline a solution (such as water) is. Water that has a pH above 7 is considered alkaline (or basic), and pH levels below pH are considered acidic

The pH of hot tubs should be between 7.4 and 7.6 on the pH scale. Therefore, the ideal water level inside should be slightly alkaline. 

Total Alkalinity 

Before we dive any further, it is important to understand total alkalinity. The total alkalinity of water is the capacity that water has to neutralize acids. 

When it comes to measuring the pH of your hot tub water, total alkalinity should be your starting point, as typically, it is difficult to adjust the pH level of hot tub water. 

The most crucial step to having a well-maintained hot tub is to achieve optimal total alkalinity before you start adding any other chemicals to the water. 

Total Alkalinity In Hot Tubs

Upon measuring the total alkalinity, the measurement should be between 80 and 120 parts per million (PPM).

When adjusting the total alkalinity level inside a hot tub, always start with small doses of the product you are using to increase or decrease the pH. Also, allow plenty of time for the water to circulate and settle before measuring the level again.

Once the total alkalinity level is stable and within the above range, you can start testing the pH level of the hot tub water. Often, once the total alkalinity level is within range, the pH level will automatically correct itself without having to add any chemicals or alkaline water. 

Why Do Hot Tubs Suffer From A Low pH Level?

Water chemistry inside hot tubs and swimming pools will constantly change if monitoring and maintenance are neglected. 

If the pH in your hot tub has had a recent nosedive, then it is most likely down to bather load. Yes, that’s correct! The more people who relax in your hot tub, typically, the lower the pH of the hot tub water. This is because an increase in hot tub bathers (natural contaminants) is directly linked to more pollutants entering the water. 

People can introduce anything from hair product residue, sunblock, body oils, skin, hair fibers, and even bodily fluids such as saliva and urine. These foreign pollutants use up the sanitizer (i.e. chlorine) in the hot tub water, and if the pH levels are not restored, the pH level inside your hot tub will decrease. 

Another reason the pH inside a hot tub drops is from external pollutants and organic matter such as rainwater or backyard debris such as leaves, grass, and dirt that is blown into the hot tub water. Again, these pollutants use up the sanitizer inside the water, resulting in a hot tub with acidic water. The easiest solution to this issue is to add a hot tub cover. 

Additionally, adding too many pH reducers (acidic chemicals) such as chlorine and bromine will decrease the pH in a hot tub.

What Happens When The pH Is Too Low Inside A Hot Tub?

A hot tub with a low pH is acidic, which is not only an issue for health but can also cause corrosion on surfaces and equipment, and reduce your ability to control the total alkalinity. 

Low pH also causes chlorine inefficiency, and no matter how much you add, it won’t work in water with a low pH. This means your hot tub water will host viruses, bacteria, and pathogens which can make hot tub users very sick.

Signs Of Low pH In A Hot Tub

  • Corrosion of metal parts 
  • Scaling 
  • Foamy water
  • Cloudy water
  • Itchy and dry skin
  • Burning eyes
  • Burning sensation in the nose

How To Test Total Alkalinity And pH In A Hot Tub?

It is super easy to test and monitor these levels inside your hot tub. Total alkalinity and pH should be measured at least twice per week. 

Firstly, run your hot tub water pump for at least 10 minutes before you switch it off. To collect a water sample from the hot tub, use a sample container and submerge it at elbow depth. If using a pH sensor/meter, take the pH test kit and dip the pH probe into the water sample.

Remember to calibrate the pH meter before use. 

Once the pH probe has measured the pH level, it will be displayed on the pH meter. 

You can also use basic pH testing strips. However, they are not as accurate as a pH sensor/meter, yet they are more simple if you only have a small hot tub in your home. 

Raising pH In A Hot Tub

The water inside your hot tub should never have a low pH level for a long period. If your hot tub does have a low pH, do not worry, as the good news is there are two ways that you can raise the pH in a hot tub. 

Adding Soda Ash (Sodium Carbonate) 

Soda ash (sodium carbonate) is the most common way to raise pH in a hot tub because it has the most drastic effect on increasing pH levels in the water. 

Soda ash is a chemical that has a pH level of 11.4, making it perfect at buffering the water, and turning it more alkaline.

Another benefit of adding soda ash is the ability for it to raise the total alkalinity level. However, as mentioned, you cannot increase total alkalinity in a hot tub without it raising the pH level, so always add the soda ash slowly, measuring the pH and total alkalinity level between each dosage to make sure the total alkalinity hasn’t spiked above 120 PPM. 

A Step-By-Step Guide To Adding Soda Ash

Below are the steps to raising pH in a hot tub using soda ash. 

Step 1: Test the pH and total alkalinity level inside the hot tub. Turn off any jets and powerheads before testing the water. As previously mentioned, you can use basic testing strips or a liquid test kit. However, for very accurate and reliable results, we recommend using a digital pH meter.

Step 2: Make note of the pH level of the water.

Step 3: Measure the amount of sodium carbonate (soda ash). Now, there is no set rule when adding soda ash to hot tubs, but we always say to aim for 1 tablespoon of soda ash per 100 gallons of hot tub water. 

If you are worried or unsure, add 75% of what you think your hot tub water needs. This way, you should prevent overdosing the hot tub water, reducing the need to decrease the pH. 

Step 4:  Once measured out, add the soda ash to your hot tub, either by pre-dissolving it into a bucket of water taken from the hot tub or by pouring the soda ash directly into the tub. We always encourage diluting the soda ash first to better disperse the chemical. 

Saying that, pouring it directly into the hot tub also works fine, as long as you ensure it is mixed well to prevent granules from settling on the sides or bottom of the tub. 

Step 5: Switch the hot tub jets and any wavemakers or powerheads on. Leave these on for around one hour to ensure the soda ash is well-circulated. 

Step 6: Retest the total alkalinity and pH of the water. If the pH level is still too low, repeat the above steps. If the pH has gone past the recommended levels, you can decrease the pH by adding muriatic acid or sodium bisulfate.

Adding Baking Soda (Sodium Bicarbonate) 

Baking Soda, which is typically available in every kitchen cupboard, is another method used to raise the pH in a hot tub. It is very popular with hot tub owners and businesses, as it doesn’t increase the total alkalinity as significantly as soda ash does. However, this means that it is less effective at increasing the pH of the water. 

The pH level of baking soda is 8.3, which, if you took note above at the pH of soda ash, baking soda has a much lower pH level. So, this means that if you use baking soda to raise the pH in a hot tub, you will need to add much more.

A Step-By-Step Guide To Adding Baking Soda

Below are the steps to raising pH in a hot tub using baking soda. 

Step 1: Test the pH and total alkalinity level inside the hot tub with a basic test kit or digital pH meter. Remember to turn off any jets and powerheads before testing the water. 

Step 2: Make note of the pH level of the hot tub water.

Step 3: Just like soda ash, there is no ‘X’ amount when it comes to adding baking soda to the water, so aim for 1 tablespoon per 100 gallons of water. Adding baking soda to raise the pH in a hot tub is typically a trial-and-error approach. But do not worry, as the pH level will not suddenly spike like it can when adding soda ash. 

Step 4: Once measured, add the baking soda to the hot tub water. You can directly pour it into the water, but remember to mix it well to prevent the granules from settling. The better option is to dilute the baking soda in a bucket with a little water taken from the hot tub. 

Step 5: Turn on the hot tub jets, wavemakers, and powerheads. Leave one hour to ensure the baking soda is well-circulated. 

Step 6: Retest the total alkalinity and pH of the hot tub water, making necessary adjustments if required. 

High pH In A Hot Tub

If your hot tub has a high pH level, it means the water is alkaline, which over time, can increase water scaling, causing issues to your hot tub equipment, and putting strain on your hot tub system. 

The pH may have increased from the following factors:

  • Alkaline local water source
  • Adding too much pH increaser

If your hot tub has a high pH, lower the pH level and total alkalinity to determine which method is best. 

The two main ways to decrease pH in a hot tub are muriatic acid and sodium bisulfate. Both these chemicals are designed to lower the hot tub water’s pH level, however, make note of which chemical you are using as the dosage requirements differ.


Keeping the pH levels in a hot tub within the ideal range is essential for maintaining proper water quality. Low pH levels can cause corrosion of the hot tub’s equipment and components, and health issues for bathers such as itchy eyes and burning skin. 

Fortunately, there are several ways to raise the pH in a hot tub. These methods include adding baking soda or soda ash. With the right approach, you can keep your hot tub’s pH levels in balance and enjoy it for years to come.If you have any questions regarding the pH of water, or what water quality testing kits we have to offer, do not hesitate to contact the world-class team at Atlas Scientific.

pH Probes & Sensors

Subscribe To Our Newsletter

Get product updates and learn from the best!

More To Explore


How To Improve Pond Water Quality & Master Maintenance

Some of the practices that can be carried out include but are not limited to the regular removal of organic debris from the pond, the introduction of aquatic plants for nutrient absorption and oxygenation, and the addition of beneficial bacteria to break down waste. Constant pH, temperature, and oxygen level checks also assist in keeping


Understanding The Role Of ORP In A Reverse Osmosis (RO) Plant

Oxidation-reduction potential (ORP) or redox monitors the condition of the reverse osmosis (RO) plant. The ORP value indicates if the membrane will be susceptible to attack by chlorine or other oxidizers, which can cause significant damage, and shorten the lifespan of the RO plant, thus increasing maintenance costs. ORP is also used to detect the

Want to learn more about our products?

Scroll to Top

To track your order please enter your Order ID in the box below and press the "Track" button. This was given to you on your receipt and in the confirmation email you should have received.