Hot Tub pH Overview

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Ideal pH Range for Hot Tubs: 7.2 – 7.6

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 it clean and clear, but maintaining a proper pH level in your hot tub is essential for other chemicals to do their job effectively. Chlorine is much less effective at higher pH levels; in fact, at a pH of 8.2, chlorine is only 15% effective. For reference, this is compared to 50% effective at a pH of 7.5, so chlorine is one-third as effective at a pH of 8.2 versus a pH of 7.5.

One of the advantages of using bromine is that it is less dependent on proper pH balance than chlorine. However, for all the other reasons, you still want to keep your bromine hot tub properly balanced. The optimal pH range for your hot tub is 7.2-7.6. Is your hot tub well balanced? Find out with our Langelier Saturation Index (LSI) calculator.

If you are using a FROG® System, only use FROG Test Strips to help you dial in the low chlorine or bromine level used with FROG Minerals. With standard test strips, you could overchlorinate/overbrominate, 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 simple ways to increase your hot tub’s pH level:

1. Use a pH Increaser (Chemical Method)
The most common and effective way to raise pH is by adding a pH increaser, sometimes labeled pH Up, pH Plus or pH Raiser. The active ingredient is usually soda ash (sodium carbonate).

If you’re not sure how much to add, first determine how many gallons of water your hot tub holds using our Hot Tub Volume Calculator. Follow the product’s instructions for the correct dosage based on your hot tub size.

After adding the soda ash, let your hot tub circulate for at least 6 hours before testing the pH again. This gives the water time to balance.

2. Add Fresh Water (Natural Method)
You can also raise the pH by adding fresh water from your garden hose. Tap water usually has a higher pH and alkalinity than your hot tub water, so topping off your tub can help bring the levels back into balance.

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 pH level was low

How to lower your hot tub’s pH

  • Test your water first.
    Before adding any chemicals, check your current pH level. This helps you determine how much product you’ll need.

    • If you’re using a FROG® System, use FROG® Test Strips. These are specially designed to measure the lower chlorine or bromine levels that work with FROG Minerals.

  • Choose the right product.
    There are 2 common types of products used to lower pH:

    • Muriatic acid

    • Dry acid (sodium bisulfate)

    Both will lower your pH, but the way you add them is different, so always read and follow the directions on your product’s label.

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?

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