How to balance high pH in a hot tub - Sutro, Inc

How to balance high pH in a hot tub

Maintaining proper water balance is essential to enjoy the best experience of using a hot tub.

One of the crucial elements of water chemistry is the pH, and its imbalance can lead to health hazards and damage to the pool equipment. Let's focus on the measures to take when you have high pH in your hot tub water.

What is the cause of high pH in a hot tub? 

A hot tub's optimal water pH levels should range between 7.2 and 7.8. A pH value greater than 7.8 means that the water has high pH.

Here are the top reasons for high pH in a hot tub:

  • The water you use to fill your hot tub already has a high pH. 

  • The total alkalinity levels of the water need to be corrected.

  • Overuse of the pH-increasing chemical raises the pH levels of water. 

  • Using aerators reduces the levels of carbon dioxide in water.

Results of high pH in a hot tub

High pH in a hot tub is not suitable for your skin and pool equipment. Here's what it'll lead to:

  • Scaling of equipment: High pH results in the buildup of scales in your filters, jets, pipes, and other equipment. In the long term, it will end up in a clogged-up filter or plumbing lines, resulting in reduced water circulation or total damage.

  • Ineffective sanitizer: High pH levels in your hot tub water will make the sanitizer (Chlorine or Bromine) less effective. Improperly sanitized water can result in problems like skin irritations, algae growth, and foul odor. 

  • Skin issues: Water with high pH is likely to cause skin rashes and eye irritations. 


How can you balance water with high pH in a hot tub? 

The two most commonly used pool chemicals to lower the pH in a hot tub are muriatic acid and dry acid (commonly known as sodium bisulfate). These chemicals are also commonly referred to as ph decreasers.

Plus, the amount of the chemical to be added will depend upon the volume of the hot tub and the current pH levels. 

Here's a quick step-by-step process of how to do it:

  1. Prepare the solution of water and acid in a clean bucket. Refer to the packaging label of the pH decreaser for instructions, or use an online calculator. 

  2. Make sure the hot tub is turned on and circulating. Plus, nobody should be inside the water. 

  3. Pour the solution gradually, keeping an arm's distance between the bucket and the water surface. 

  4. Let the pump run for 5-6 hours. Then check the alkalinity and pH levels. 

Pro Tip: When preparing a solution to lower pH, always add acid to water and never the other way around. 

What can you do to prevent it from happening? 

The best way to prevent rising pH levels is to check them regularly. You can use test strips or test kits to check the pH once or twice weekly. Additionally, maintaining the alkalinity at optimal levels will keep the pH in check. 

If regular testing sounds too much work for you, use our Sutro Pool Monitor to keep an eye on the water chemistry of your hot tub. It will check the pH levels three times daily and send this information to your mobile application.

You will also receive recommendations on the amount of chemicals to add to your hot to lower the pH. 


The high pH of your hot tub water can result in scaling of the equipment, skin issues, and rendering the sanitizer ineffective.

High pH can be a result of adding excessive pH-increasing chemicals or the already high pH of water used to fill.

The best route is to constantly monitor the pH levels of the hot tub and use an appropriate acid (muriatic or dry) in the proper concentrations for treatment.

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