Hot Tub pH Overview

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Ideal pH Range for Hot Tubs: 7.2 – 7.8

Testing Hot Tub pH: Test your hot tub’s pH level regularly (ideally twice per week) with a test kit or test strips. In addition, we recommend periodically (once per month) taking a water sample to a dealer test station to verify the results.

One of the biggest parts of hot tub care is maintaining the chemical balance in your hot tub. Hot tub chemistry is not only necessary to keep your hot tub clean and safe, maintaining a proper pH level in your hot tub is essential in order for other chemicals to do their work. Chlorine is much less effective at higher pH levels; in fact, at a pH of 8.2, chlorine is only 15% effective. One of the nice things about using bromine is it is not as dependent on proper pH balance as chlorine is but for all the other reasons you want to keep your bromine hot tub properly balanced. The optimal pH range for your hot tub is 7.2-7.8. Is your hot tub well balanced? Find out with our Langelier Saturation Index (LSI) calculator.

If using a FROG® System, use only FROG Test Strips to help you dial in the low chlorine or bromine level used with FROG minerals. With standard test strips you could over chlorinate/brominate which wastes money. Using FROG Test Strips can help your bromine cartridges last up to 50% longer!

Low pH

A low pH level means your hot tub water is acidic, which can not only cause corrosion of surfaces and equipment, it can also reduce your ability to control Total Alkalinity and cause an uncomfortable experience for your family and guests, as acidic water will sting eyes and remove the natural oils on skin, leaving it dry and itchy.

Why is my hot tub’s pH low?
Many things can lower the pH in your hot tub:

  • You might have added too much pH reducer in an attempt to lower the pH of your hot tub
  • Your local water source may have a low pH, this may be the culprit if you are continually having to add pH increasing chemicals
  • Heavy hot tub usage can introduce a large amount of natural contaminants (i.e. body oils, sweat, etc). All of these natural contaminants can lower the pH level in your hot tub
  • Organic matter such as grass, insects and dust are common organic matter that can lower the pH
  • Shocking your hot tub will lower the pH regardless of what type of shock you use

How to raise your hot tub’s pH
There are two main ways to raise/increase the pH in your hot tub. The first is to use chemicals, typically called a pH increaser, pH plus or pH raise, the most common of which is soda ash. If you don’t know how many gallons of water are in your hot tub, you can calculate it here with our Spa Volume Calculator. Once you’ve added the soda ash, you’ll want to wait at least 6 hours before retesting your hot tub’s pH level.

The second way is to raise your hot tub’s pH by adding new water. Water from your hose is typically slightly higher in alkalinity than your hot tub water should be, thus adding new water should bring up your hot tub’s pH level a bit.

High pH

When your hot tub has a high pH level, it means the water is basic and over time high pH levels can cause the water to scale on your filters, plugs, pipes, jets and other equipment. Water scale can reduce the water circulation, thus increasing water pressure within the circulation system and putting strain on your hot tub equipment.

Why is my hot tub’s pH high?
Below are a few reasons why your hot tub’s pH level may be a bit high:

  • Local water source may have a higher than normal pH level
  • You might have added a little too much pH increaser when you saw your hot tub’s pH level was low

How to lower your hot tub’s pH
First test your hot tub’s pH level, to help you determine the best type of chemical to use to lower your pH. If you’re using a FROG® System use FROG® Test Strips which are designed to dial in the low chlorine or bromine levels used with FROG® Minerals.

There are two main chemicals typically used to decrease pH in hot tubs, muriatic acid and dry acid (also known as sodium bisulfate). Although they are designed to do the same thing, pay attention to which chemical you are using, because how you add the chemical differs.

Struggling with pH? Did you know FROG Fresh Mineral Water Systems help maintain pH balance for cleaner, clearer and softer hot tub water with 50% less bromine?