Low pH In Your Hot Tub? Here’s How To Fix It

Proper pH levels in your hot tub are crucial for avoiding bacteria growth and contamination. Knowing when and how to test those levels is not only a good health practice but also one that can extend the life of your hot tub, since a low pH can actually corrode its components. So, if you’ve got low pH levels in your tub, how can you fix it?

A low pH level (below 7.2) means that the water in your hot tub is too acidic, while a high pH reading (above 7.8) is considered too alkaline. Unbalanced pH levels can cause physical irritation to the eyes and skin as well as damage to the tub. Use a pH increaser or decreaser to correct the pH levels.

If your pH is too low or too high, it should be corrected as soon as possible. After all, no one wants to swim in a pool of their own bacteria and filth! Let’s take a closer look at how pH levels affect your hot tub and how to keep them balanced.

What Is pH?

Hot Tub Water Quality Check by Using Chemical Testing Kit

The pH scale is used to measure how acidic or alkaline (basic) a fluid is. The scale measures from 1 to 14, with water being at pH level of 7. Since water is the purest form, it’s the basis of the pH scale, with anything above 7 being considered alkaline and anything below considered acidic. 

For a hot tub in particular, you should try to keep the pH level between 7.2 and 7.8. When the pH is too low, it means the water is too acidic, which could cause your eyes to sting and your skin to itch. Having a low pH isn’t safe for use and should be corrected as soon as possible.

In addition to determining how acidic or alkaline your hot tub is, testing the pH level is important for assessing whether there’s any bacteria or other possible contaminants in the water.

Acidic vs Alkaline: What’s the Difference?

A reading of below 7 on your pH testing strip means that your hot tub is too acidic and needs a higher pH. Anything above 7 is considered alkaline. The difference between these two readings can affect how the hot tub’s water reacts to chemicals, but also how your body reacts to the water.


With a reading below pH 7, your hot tub is considered acidic, which means it’s unbalanced. A low pH reading can pose a risk to both your hot tub and bathers.

Acidic water can stop the sanitizer’s ability to clean the spa, making bacteria growth and other harmful contaminants more likely. The hot tub basically becomes a breeding ground for dangerous bacteria that can make you and anyone else that uses it sick. 

With high levels of contamination — depending how long your pH has gone unchecked — you aren’t just looking at itchy skin and burning eyes. On top of health concerns, acidic water can also cause corrosion and pose a significant risk to any hot tub components that come in contact with the water.


Receiving a high reading on your pH test means it’s above 7.6 and is considered alkaline or, as some people call it, basic. Much like its acidic counterpart, an alkaline reading will make the sanitizer useless, and that will then increase the risk of bacteria growth and contamination. 

To put an unsanitized hot tub into perspective, it’s the same as sitting in the same bath water for a month, with all the bacteria growing from each use and staying on your skin. 

Alkaline water also allows for scale to build on the walls of your hot tub. You might recognize scale on taps, in the shower, and around your sinks if you have hard water. It basically means that calcium has built up and hardened, though it can really cake itself on and prove difficult to get off without the proper equipment. 

A visual indicator that your hot tub water is alkaline is a cloudy look, when it should always be clear. If you notice your water has become cloudy and extra sanitizer isn’t dealing with it, then try testing your pH levels with a test kit (on Amazon). You’ll probably find that the water has turned alkaline. 

How to Adjust the pH in Your Hot Tub

Spa Jacuzzi Hot tub water quality testing

The process for adjusting your pH depends on whether you have acidic or alkaline pH readings. If your pH levels are too low, then you’ll need a pH increaser (on Amazon). This will gradually increase your pH level to 7.2 or above, but you’ll need to leave it for 30 minutes before using the hot tub again. 

After the 30 minute wait, retest your pH level in the still water without any jets running to check that the pH increaser hasn’t negatively impacted the alkalinity and other water levels. 

If you have a high pH of 7.6 or above, which is considered alkaline, then you’ll need to use a pH reducer (on Amazon). Much like the pH increaser, you’ll need to add the product and then leave it for 30 minutes to gradually reduce the pH level in your hot tub.

After the 30 minute wait, retest your pH levels with no running jets to make sure the product hasn’t affected other water levels. 

Does Shock Raise Your pH?

Shocking your hot tub is a great way to help maintain its balanced water chemistry and get rid of any growing algae. It over chlorinates or over oxidizes the water for a predetermined amount of time to help reset water levels.

Doing this forces the elevated levels of chlorine to reach a breaking point where the organic material in the water is satisfied. At that point, the chlorine levels are then lowered and algae is usually eliminated. 

There are three types of pool shocking that you can use, all of which can affect your hot tub pH, so it’s best to do your research and test your pH both before and after shocking the tub.

Calcium Hypochlorite

This shock method is the most powerful and fastest shocking technique available. It’s both an oxidizer and sanitizer, and it’s quick dissolving. It’s most frequently used when people discuss shocking their pools or hot tubs.

Keep in mind that this method will raise your pH slightly, so make sure you’re adjusting your pH to accommodate this change. 

Dichloroisocyanuric Acid

Also known as dichlor (on Amazon), this method contains both chlorine and cyanuric acid, which will raise your cyanuric acid levels over time. It’s both a sanitizer and oxidizer like the above method, but it will lower your pH instead. 

Sodium Monopersulfate

The last method is known as MPS shock, and it’s an alternative method to chlorine shock. MPS is an oxidizer but not a sanitizer, and it won’t affect your pH levels like a chlorine shocking method would.

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