What is spa water alkalinity and pH? (Why it’s important, how to measure, adjust and more…)

Understanding water pH, alkalinity, and test strips can be complex, so we've created a guide to help you understand all the terms and show you how to measure and adjust your pH and alkalinity.

In this article, you'll learn what spa alkalinity and pH are in your spa water, and why they matter.

 

 

If the pH and alkalinity of your spa water is not kept at the appropriate level there is a greater risk of damage to the spa equipment. This includes your spa heater element, spa pump seals, as well as other internal surfaces.

 

Read on to find out more about how to adjust your pH and alkalinity and what the correct levels should be.

 

This guide is for general reference only. Always follow the directions on your chemical container label. Always follow the directions on your chemical container label.

 

What is the difference between pH and total alkalinity (TA) in a spa?

Some believe pH is the most important component of water balance, but it is even more important to consider the total alkalinity of your spa water.

If you delve in your memory back to high school chemistry, you may remember pH is the measure of how acidic or basic a solution is on a scale of 1 to 14. 1 being completely acidic, and 14 being completely basic.

Spa total alkalinity (TA) measures the ability of your water to neutralise acids, or resist changes to your water's pH. If the total alkalinity in your spa water is too low, your water pH can easily fluctuate and potentially become too acidic easily.

You should always test and adjust the total alkalinity in a spa before testing and adjusting any other water balance levels including pH.

 

Why are spa alkalinity and pH levels important in my spa?

If the pH and alkalinity of your spa water is not kept at the appropriate level there is a greater risk of damage to the spa equipment. This includes your spa heater element, spa pump seals, as well as other internal surfaces.

In addition, you will have trouble keeping your water clean and clear if the total alkalinity and pH are not set at the right level.

 

What is the normal range for Total Alkalinity (TA) in my spa pool?

The Total Alkalinity readings for your spa water should be between 100-150 mg/L

If you believe your pH is a bit high, adjust your TA up slightly above 120 PPM because chemicals that lower pH, lower alkalinity at the same time.

How do I raise total alkalinity in my spa pool?

Use an alkalinity increaser like Sodium Bicarbonate to increase the alkalinity in your spa or hot tub water. Note that an alkalinity increaser will also increase your water pH.

 

What is the best Alkalinity Increaser for my spa?

We have a selection of alkalinity increasers available which we recommend and are approved for all Spa World spas and swim spas - Jacuzzi, Vortex, Fisher.

 
      

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Alkalinity increasers for chlorine free / hydrogen peroxide spas

 

 
 
     
              

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If the total alkalinity in your spa is not at the correct level it can result in these issues:


What are the effects of high Total Alkalinity in my spa pool?

  • The pH is difficult to regulate.
  • Scale forms on spa surfaces.
  • The water becomes cloudy.
  • Skin and eye irritation including rash.
  • Inefficient Sanitiser.


What are the effects of low Total Alkalinity in my spa pool?

  • pH is difficult to balance and change quickly.
  • Corrosion on metal equipment.
  • Skin and eye irritation including rash.

 

 

What should the pH level be in a spa?

A pH reading in the range of 7.4 - 7.6 is ideal for your spa or swim spa.
If your reading is below 7.4 then your water is too acidic and you need to add a pH increaser or Alkalinity increaser which will raise the pH and Total Alkalinity.
if your spa water pH reading is above 7.6 then it is alkaline and needs a pH Decreaser

 

Does high pH cause cloudy spa water?

Yes. One of the results of high pH can be cloudy spa water. If you are experiencing cloudy water in your spa or hot tub, follow the steps above to test your water, then adjust your pH down using one a pH decreaser.

 

What's the best way to test pH in a spa?

 

How to use test strips in a spa or hot tub

 

Use test strips to test for pH and alkalinity in your spa or swim spa water to ensure your water is balanced correctly.

To test follow these steps;

  1. Ensure your test strips are not old, expired or damp
  2. Test in natural daylight for best results
  3. Remove a test strip from the test strip bottle with dry hands
  4. Dip the test strip in your water and move it gently through the water for 5-15 seconds (follow the directions on your particular bottle to ensure you do this correctly)
  5. Compare the colours that appear on your test strip with the colour chart on the back of your test strip bottle to get your pH and alkalinity reading.
  6. Once you've checked the results, adjust your spa water accordingly. (Follow the directions on your chemical container).

 

 

Reading test strips for pH and Alkalinity

An example of the colour chart on the back of a test strip bottle.

 

What are the best test strips for chlorine spa water?

 

 

 
     
      

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What are the best test strips for hydrogen peroxide / chlorine free spa water?

We recommend the Poppits 4 way test strips for testing your spa water if you are using a chlorine free / hydrogen peroxide sanitiser.

 
 
     
              

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How do I lower pH in my spa water?

If the results of your testing your spa or hot tub water show that your pH is too high, then you'll need to add a pH decreaser product like Sodium Bisulphate to your spa water.

 

Recommended pH Decreasers

 
       
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How do I increase the pH in my spa water?

If your spa water pH is too low, use a pH increaser product (Sodium Bicarbonate) to increase the pH. Sodium Bicarbonate will also increase the Total Alkalinity in your spa water.

 

Recommended pH Increaser products (also Alkalinity Increasers)

 
      
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What is the best pH increaser for Poppits chlorine free sanitiser?

 

 
 
                               
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What are the effects of high pH readings (above 7.6)?

 

  • Poor efficiency of sanitiser (you'll need to add more sanitiser to maintain your water)
  • Cloudy spa water
  • Scale formation on spa surfaces
  • Reduced spa filter life
  • Skin and eye irritation including rash



What are the effects of low pH readings (below 7.4)?

  • Poor efficiency of sanitiser
  • Corrosion develops on metal equipment
  • Skin and eye irritation including rash
  • Stained plaster (Concrete spa or pool)
  • Severe reduction of Total Alkalinity

 

 

In Summary

 

Hopefully you now have a much clearer understanding of the difference between pH and alkalinity in your spa water. You'll also understand why it's important to test and adjust these in your spa to ensure your water is kept in pristine condition.

Remember to start with testing and adjusting the total alkalinity then balance your pH.

Using a chlorine-based sanitiser will change the pH in your spa, so always test your pH after you have added sanitiser.

 

Got more questions? 

Talk to us on live chat, or email us your spa chemical questions and we'll be happy to help!

 

                               
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