How to Lower Alkalinity in a Hot Tub?


It’s important to know how to balance the water in your hot tub. Learning how to lower alkalinity in a hot tub is easier than you might think. Once you learn how to achieve the desired level, it’s also easier to maintain it.

We’ll walk you through everything you need to know to achieve and maintain balance in your hot tub.

What is Alkalinity?

Alkalinity is the measurement of the water in your hot tub to determine how it is able to neutralize acids. A proper pH balance is critical so that you have the comfortable soaking environment that you have come to expect.

The alkalinity is sometimes referred to as the “buffer.” The reason for this is to ensure that your water is capable of resisting drastic changes in pH levels.

Test strips can be used to tell you what the alkalinity of the water is. Your goal should be to maintain it between 80-120 ppm.

Why is Lower Alkalinity Important?

If you have high alkalinity, you’ll notice problems with the cleanliness of your tub and the water itself. You might see scale forming along the sides, calcium buildup around the jets, and even cloudiness within the water.

In some instances, there may be so much calcium that you see yellowish flakes swimming around in the hot tub water.

A deep cleanse can help you to reverse any damage. However, if you’re not careful about pH levels, you can create a significant amount of damage that will affect overall functionality.

It’s important to note that you don’t want to lower your alkalinity too much, either. If it’s too low, the sanitizing solution you add to the water won’t be effective. The water may look a little green and it can even result in mold or mildew growth.


What Causes High Alkalinity?

Now that you know why high alkalinity is bad, you need to know what causes the PPM to go higher than desired.

Some of the most common reasons include:

  • Adding too many chemicals to your hot tub
  • Lotion, sweat, and other products you put on your body get dissolved into the water
  • Your water source may have a high alkaline rating

If you find that your alkalinity is constantly running on the higher side, it may also be a good idea to have a technician come out. We can run some diagnostic tests and help you with your weekly alkaline testing.

Tips on How to Lower Alkalinity in a Hot Tub

There are plenty of ways to test the alkalinity so that you know if it has to be lowered.

First, plan on testing the water in your hot tub when the water is hot. Test it one to two times a week based on usage. It doesn’t take long for the alkalinity of the water to change.

If you’re above 120 ppm, you’ll want to work on getting the alkalinity lowered. Otherwise, your pH levels could quickly become unstable.

Here are a few things that you can do to lower alkalinity:

  • Add sodium bisulfate to the water
  • Add muriatic acid to the water
  • Schedule a service appointment

The trick is to test, test, test. Additionally, you’ll want to know the basic details of your hot tub (total gallons, etc.) so that you can make the necessary calculations. You cannot simply drop in a pinch of sodium bisulfate or muriatic acid and hope that you’ve lowered the alkalinity sufficiently. Careful measurement will make all the difference – and deliver the best possible results.

Get Help with pH Levels and More

When you are struggling to maintain the desired pH levels or feel overwhelmed by the various chemicals that can go into your hot tub, call us. At Ajax Pool & Spa, we have technicians who can provide maintenance and offer guidance. Once we get your alkalinity lowered, you can enjoy your hot tub more.

There’s no reason to fight with your hot tub. We’ll set you up on a schedule so that we can come out to work with you on not only chemical levels but also overall hot tub maintenance.