Guide to pH Levels in Hot Tubs

Ensuring your spa's water is balanced plays a crucial part in maintaining a clean and healthy hot tub. By keeping on top of its maintenance, you'll be saving yourself the hassle and expense of issues occurring further down the line.

When first purchasing a hot tub, the initial information about water chemistry might feel a little daunting. But there's no need to worry; this guide will demonstrate how simple and easy it is to balance the pH of your water and explain why it's so important.

Here at 1st Direct Pools, we pride ourselves on our expertise in swimming pools and spas; for any assistance on what hot tub chemicals or products to purchase, please refer to our blog or contact a member of our team who will be happy to help!

Read our guide to hot tub chemicals

What Does a Hot Tub’s pH Mean?

Part of the responsibility of owning a hot tub is testing the spa’s water; you can do this with hot tub test strips or liquid test kits.

The test results will indicate how balanced the water is and what chemicals you will need to use to rebalance the water.

The pH balance will specify the acidity or alkalinity of the spa's water. The pH is measured on a scale from 0-14:

  • A measurement of less than 7 is deemed acidic.
  • A measurement that is higher than 7 is classed as alkaline or basic.
  • A measurement of 7 is considered neutral or balanced.

What pH is Needed for a Hot Tub?

The perfect pH result for a hot tub can range from 7.4-7.6. If the pH level reads outside of the appropriate range, it's essential to take steps to help balance your water chemistry. Doing this will avoid any potential issues that can damage your spa, which can result in expensive repairs.

What Happens if the Hot Tub’s pH Level is Too Low?

A pH reading below 7.4 will indicate a low pH level, meaning the hot tub water is acidic. Acidic water creates an environment that stops sanitisers, such as chlorine tablets, to work effectively.

Conditions that create these ineffective environments for sanitisers increase the bathers' chances of being exposed to bacteria that can potentially be harmful.

Low pH levels will also cause corrosive activity within your hot tub, damaging the hot tub's equipment and resulting in extra costs.

What Happens when the Hot Tub’s pH Level is too High?

Spa water with a pH level above 7.6 is often described as basic. This measurement is an indication of poorly sanitised water.

When your hot tub water is basic, you might encounter cloudy water. You might also notice a build-up in scale that can accumulate along the water's surface due to calcium hardness that increases due to a high pH.

A high pH level may also cause bathers to experience itchy skin and burning eyes and result in premature equipment failure.

A wooden hot tub with a scenic view

What is Total Alkalinity?

Total alkalinity is a measure of the dissolved alkali in a body of water, which helps to prevent any change to the pH when adding other chemicals.

It's important to check the total alkalinity of your hot tub before adding any other chemicals, as it will help prevent any vast fluctuations in your spa’s pH level.

What Should the Total Alkalinity be in a Hot Tub?

To prevent the effects of too high and low alkalinity, aim to keep total alkalinity between 80-120 ppm. Adjust the total alkalinity in small measures and allow each dose to circulate before testing again.

What to Do if Total Alkalinity is Low

Low alkalinity can cause inconsistent pH levels, which means the pH levels will be easily altered by the slightest addition of an acid or base. The pH levels are likely to drop erratically, leading to various problems, as mentioned above.

What Happens if the Hot Tub’s Total Alkalinity is Too High?

High alkalinity will typically lead to high pH levels. It's essential to be conscious of this as although the water might not be corrosive, high pH can result in a build-up of calcium.

High alkalinity or calcium build-up can become visually evident if left untreated, resulting in cloudy hot tub water, and a build-up of scale will start to form.

How Do I Balance the pH in my Hot Tub?

Before attempting to perfect your pH levels, ensure your total alkalinity is in range. Correcting the alkalinity can help stabilise your pH and prevent you from unnecessarily wasting pH chemicals.

When addressing your spa’s pH level, it's important to note that pH increasers and pH decreasers will affect the alkalinity.

How do You Raise a Hot Tub’s pH level?

There are several ways to raise the pH levels of your spa’s water.

You can use chemicals such as a pH increaser, also known as pH plus, pH raise or soda ash. However, note that soda ash can also raise the alkalinity of the water.

To effectively raise the pH level, you must follow the manufacturer's instructions. Revising how many litres of water your hot tub uses will provide an appropriate solution for the water.

Another option is to drain and add fresh water to the hot tub. This option will raise the pH level, but it will also require replacing other essential chemicals.

How Do You Lower a Hot Tub’s pH Level?

If you're looking to lower the pH level of the water, you can choose between muriatic acid and dry acid, sometimes known as pH minus. Both differ in how each is applied to the water, so following the manufacturer's instructions is important. The most popular option is to use dry acid.

Using a pH decreaser will often lower your total alkalinity, so you may need to test the waters TA and increase it afterwards.

Muriatic acid is an alternative that will also decrease both the pH and the alkalinity. When using Muriatic acid, ensure you dilute it before adding it to the hot tub. Once you have added it to the hot tub, you will need to aerate the water by running the jets. Allow the water to be left overnight before testing.

We hope this guide helps you with your hot tub's pH levels. If you're still in need of assistance, you can contact a member of our team or browse our blog for more information.

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