How To Raise Alkalinity In Hot Tub?

Maintaining the correct level of alkalinity is critical for equipment which is used for water circulation, and a good example of such an equipment would be a bathtub. Alkalinity is the ability of the water to keep the elements less acidic by maintaining the right pH level.

Low alkalinity is proven to be harmful to your skin and eyes. At the same time, it damages your precious tub in the long run.

Hence sustaining the correct level of alkalinity is a must for the tub owners. For beginner’s, alkalinity or pH level – all these terms might sound alien or right out of a chemistry experiment!

But in reality, these are some basics terminologies for which you shouldn’t need any academic degree to understand. Throughout this article, I have focused on explaining the process of raising the alkalinity of a hot tub in the easiest way possible.

What Is Alkalinity?

Alkalinity measures the water’s ability to neutralize acidity by managing its pH levels.

It acts as a buffer if any change is made in the water’s pH value. So, alkalinity helps to keep the pH level in water stabilized and also less acidic. There are 3 primary types of Alkalinity such as:

  • Bicarbonate
  • Carbonate
  • Hydroxide

What Is pH?

The pH of the water determines which type of alkalinity is dominant in water at the moment. pH is a shortened form of "power of hydrogen" which is a measure of the concentration of Hydrogen ions in water or any liquid.

Water solution with a high level of Hydrogen ion have a low pH, and vice versa - little Hydrogen ion tend to have a higher pH.

Roles Of Alkalinity And pH In Water

Alkalinity and pH balance are the two crucial factors for determining the suitability of water.  Total alkalinity and pH measurement are not a relative measure.

Water with high alkalinity always has a pH value of 7 or more, but water with high pH still does not have high alkalinity. pH range is ideal between 7.2 and 7.6.

If the number is below 7, the water is considered acidic and too high is regarded as ‘basic’ meaning it contains base elements according to the pH scale formation. 

The measure of alkalinity is expressed as "ppm of Calcium Carbonate," and the desirable range is between 80-120 ppm.

Adverse Effects Of Low Alkalinity On Equipment

Here are some of the effects of low alkalinity on equipment;

  • Corrosion of the Surface: The surface of the tub can be eroded by acidic water damaging the protecting layer of the tub.
  • Risking Heating Elements: Any kind of metal components like pipes, heaters can be rusty if it is in touch of the water with low alkalinity. Apart from property loss, it may also create risk for the user of getting burnt if the pipe breaks down while using.
  • Scale Formation: Calcium scaling is a common phenomenon for such a case of low alkalinity. It makes it difficult to keep the surface clean.
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    Metal Stain: As the metals began to scour, it leaves some stubborn metal stain which makes the tub look dirty and difficult to take off.

Adverse Effects Of Low Alkalinity On Human Health

  • Stinging eyes and nasal passage
  • Redness and irritation on eyes
  • Dry itchy skin
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    Hair fall
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    Skin infection like spots and allergy.

Chemical Free Process To Raise Alkalinity

Commonly harsh chemicals are being used to raise the Alkalinity of a hot tub which might irritate our skin. But the good news is it can be done through a natural process, using one ingredient only and that holy grail is baking soda (Sodium bicarbonate)!

All we need is just a water testing strip and some baking soda. The measurement: 1 tablespoon of baking soda is required for 100 gallons of water. After that do as follows:

  • Test the water pH level using a water testing strip.
  • Mix the baking soda with water according to the requirement stated above.
  • Turn on the hot tub jet and allow the ingredient to circulate in the water for two to four hours.
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    Retest the pH level. If it’s not within the desired range, keep running the process. Eventually, it will reach the desired level.

Maintaining the desired pH level is very important for the safety of our health. One simple technique you can follow is draining and refilling the water regularly to keep the pH level at a preferred quantity without any extra effort.

However, through a water strip test we can be certain of it and if required, the alkalinity can be raised through the above-mentioned simple process.

Artificial Process To Raise Alkalinity

We have already mentioned that the alkalinity level should be kept between 80-120 ppm. If it's below that then alkalinity can be raised using different products available in the market which are specifically manufactured for this one job.

But you should apply it with caution in cases of pregnant women.

Alkalinity Raising Process

  • Test the alkalinity of the water using a testing strip.
  • Add one capful of Alka Plus to the tub water. It usually increases the alkalinity level one square on the test strip.
  • Turn on the jet and let it circulate in the water completely. Let it rest overnight as it is better to raise the alkalinity gradually.
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    Check the alkalinity level again the next morning. If it still did not reach the desired level, re-run the process.

Water Clarity Process

  • After adjusting the alkalinity level, if still, the water looks green adjust the sanitizer level. For that add 30 gm, 1 capful of sun boom to the water.
  • Then add 100 gm, 4 capfuls of spa shock to the water to regain water transparency.
  • After each process turn on the spa jet and let the water circulate at least for 20 minutes.

After completing the process, it is crucial to let the air pass through your tub. The confined area may create a toxic reaction which is harmful for a human. 

Tips And Best Practices

  • Never use pool chemicals in a hot tub. Chemically, the substances are the same but the concentration is denser.
  • If you want the chemicals to work efficiently, change the tub water frequently.
  • At least twice a month, have your tub alkalinity checked by a professional.
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    In case your test strip is continuously giving a low reading, then the strip might be expired. To be sure you can collect a few other water samples from nearby sources and check again.


A hot bath in a spa tub feels heavenly after a tiring day. But this pleasant experience might turn into a nightmare if proper care is not taken. It is a must to check alkalinity level regularly and based on that, steps should be taken to maintain the desired alkalinity level.

Our readers can follow the above-mentioned processes to maintain their tubs. If in doubt, they can take professional help as well. The bottom line is, alkalinity of the tub water should always be tracked for safety purposes.

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