There’s no better way to unwind and relax after a long day than to take a dip in the hot tub. Owning a hot tub is a luxury that not many people can afford, but if you are one of the lucky ones, you know how amazing it feels to sit back & let the bubbles envelop you.

While owning a hot tub is undoubtedly one of the best things out there, most hot tub owners will tell you that it comes with a fair bit of maintenance. Keeping your jacuzzi in top shape can take some work. One of the most important things to keep in mind is keeping the correct balance of total alkalinity.

What is water alkalinity & how to lower it and balance it? We are here to help you with that! Keep reading to learn all about alkalinity in hot tubs.

What is Water lower Alkalinity in Hot Tubs?

Water alkalinity is a measure of how well the water in your hot tub can neutralize acids. It plays an important role in balancing pH level and helps the water resist massive changes in pH. For that reason, some people like to call alkalinity a “buffer”, because it’s a natural means of protection from acids in the water.

When the levels of alkalinity in the water become unbalanced, your hot tub is put at risk. High alkalinity may have a negative effect on the appearance of your hot tub, such as causing cloudy water. What’s worse, it might actually harm your skin.

Both high and low levels of alkalinity can be harmful to your health. You may experience burning eyes, itchy skin, and irritation that results in dry, flaky skin.

Maintaining a balanced total alkalinity is a crucial part of hot tub water care. In order to keep the hot tub water clear, we recommend that you take some maintenance steps that will help you with that.

What happens if alkalinity is too high in a hot tub?

When alkalinity levels are too high in your hot tub, the result is sometimes visible to the naked eye. What high alkalinity does is it reduces the effectiveness of the sanitizer you use & add to your hot tub water. Sanitizers underperform when used in unbalanced waters, which is why total alkalinity is so important.

You will easily be able to tell when the alkalinity balance is too high — the water in your hot tub will develop a green hue. This is the direct result of really high pH levels in the water.

When the pH in your hot tub water is high for a prolonged period of time, calcium begins to build up. From that point on, scale will begin to form, and the water will turn cloudy. Calcium can also cause the water to develop yellow flakes, spoiling the aesthetic of the jacuzzi.

If these issues are not dealt with in a timely manner, calcium & scale build-ups will eventually damage your spa’s jets and equipment. Some possible effects include clogged filters, lowered performance of water sanitizers like chlorine or bromine, and more.

What happens if alkalinity is too low in a hot tub?

If high alkalinity sounds bad, wait till you hear about low alkalinity. Surprisingly enough, that is the worse one of the two.

Low alkalinity causes rapid fluctuations in pH levels, which is bad for both your hot tub and your skin. If alkalinity is too low, it causes the hot tub water to turn green — that’s the first adverse effect. It’s a downward spiral from that point on when it comes to low alkalinity.

If you do not tend to this issue quickly, low alkalinity levels will eventually impact not just the surface of your hot tub, but also corrode the internal equipment of the tub. This can sometimes result in a complete breakdown.

What is pH?

pH stands for “potential of hydrogen”. What it means is that pH is the measure of how much hydrogen ion is present in your hot tub water. This translates to whether your water is acidic, basic, or neutral.

When it comes to ideal pH levels, anywhere between 0 and 7 is considered to be acidic, a perfect 7 is considered neutral, and between 7 and 14 is referred to as basic.

What’s the Perfect Balance of Alkalinity?

Now that you know how important it is to keep alkaline levels balanced, the question arises — what’s the ideal level of total alkalinity (TA)?

Long story short, total alkalinity should always be kept at 80-120 ppm (parts per million). PPM, or parts per million, can also be referred to as milligrams per liter (mg/L). This measurement stands for the mass of chemicals or contaminants per unit volume of water.

As long as you strive to remain within the 80-120 ppm range, the water in your hot tub will be fine. However, when the measurement rises above 120 ppm, you’re dealing with high levels of alkalinity. Conversely, anything under 80 needs to be addressed with low alkaline balance methods.

How To Test Alkalinity & pH Levels in Hot Tub Water?

Your first step to a crystal clear hot tub water is to test the alkalinity. Fortunately, testing alkalinity is very easy and can be done on your own without any help from professionals.

The best way to test alkalinity balance is to use hot tub, pool, and spa test strips. These special strips test the levels of pH, total chlorine, free chlorine, bromine, total alkalinity, total hardness, and more. As the testing has to be done quite often, we recommend picking up a large pack of testing strips. It doesn’t hurt that they are as affordable as they are!

Using test strips is extremely easy. Here is a step-by-step tutorial on how to test alkalinity levels in your hot tub:

  • First, get a reliable set of test strips that checks not only for total alkalinity, but also for pH, chlorine, and more. If you want to be extra safe, you can pick up two different strips from different brands and check with both.
  • Next, familiarize yourself with the instructions the brand provides. Different tests may vary in how they are performed, so don’t skip this step.
  • Most commonly, what you will have to do next is to simply dip the test strip in your hot tub and leave it there for a moment.
  • Once you take the strip out of the water, take a look at the coloring chart.
  • Compare the colors on your test with the color chart on the bottle.
  • Corresponding colors will show you the current levels of contaminants in the water.

It’s easy as pie! As long as you test often enough, you will never have to worry about alkaline unbalance in your hot tub.

Before you jump in for a dip in the hot tub, do you know how to lower your alkalinity if it proves to be too high?

How do I Lower My Alkalinity?

As we mentioned in the sections above, the ideal alkalinity level is around 100 ppm. If your alkalinity proves to be higher (above 120 ppm), it’s time to act — and be quick. The longer you ignore the issue, the bigger the problem will prove to be in the future.

The easiest way to lower hot tub water alkalinity is to simply add sodium bisulfate to the water. If that doesn’t make much sense to you, don’t worry — we will guide you through the process step-by-step. Keep reading to learn how to lower water alkalinity in a hot tub.

Calculating sodium bisulfate requirements

Before you begin the actual process of lowering alkalinity, you need to calculate how much sodium bisulfate you need to add. This is closely tied to the volume of water in your tub & how much you need to lower the total alkalinity (TA).

In order to calculate exactly how much sodium is going to be needed, follow this formula:

  • In order to lower the alkalinity of 1,000 gallons of water by 10 ppm, you need to add 3.5 oz of bisulfate.

Knowing that, you will be able to calculate just how much you need for your particular tub. To give you an example, lowering the alkalinity of 500 gallons of water by 10 ppm would only require 1.75 oz of sodium bisulfate. 500 gallons of water is close to the average water capacity in a six-person hot tub. If your hot tub is a small model for two, you will require much less than that — about a third.

Lowering alkalinity levels

Once you’ve done the measurements, it’s time to get to work. Below are the steps you need to follow to alkalize the water in your hot tub correctly.

  1. Measure the correct amount of sodium bisulfate.
  2. Set your tub to circulate.
  3. Once the circulation begins, pour in the chemical. Allow it to keep circulating within the bath for around 20 minutes. Next, shut it off completely.
  4. Wait for the water to slow down and then come to a halt.
  5. When the water has completely stop moving, leave the tub for at least an hour.
  6. Next, when the hour is up, test the water yet again using a testing strip.
  7. The alkalinity should reach balanced levels at this point. However, if it’s still too high, lower it using the above steps once more.

As soon as you manage to reach the desired total alkalinity, leave your hot tub overnight without using it. Next, test it once more the next morning. If it stays at the correct level, you’re done; if not, simply repeat the process.


As you can see yourself, lowering total alkalinity in a hot tub is not a difficult process. Sure, it requires a bit of time, but the results are often spectacular.

If you find yourself still wishing for answers on certain subjects, make sure you read our handy FAQ below!

How do I lower the alkalinity in my hot tub without pH?

Fortunately, lowering the alkalinity in your hot tub should not affect the pH levels in any negative way. If anything, balancing it out will only improve the pH levels and take them from acidic to normal in no time at all.

Does vinegar lower alkalinity in a hot tub?

A common myth that people tend to repeat is that vinegar, supposedly, lowers total alkalinity in a hot tub. As nice as that would be, it’s simply untrue. Vinegar only lowers the pH, but lowering the pH while maintaining high alkalinity will not be helpful at all. As such, vinegar can only harm your hot tub as opposed to helping you.

Can I put vinegar in my hot tub?

You can, but the question is, should you?

Many people use vinegar, or other acetic acids, in order to clean their hot tub and other surfaces. Vinegar acts as a bit of an all-purpose cleaner, and as such, it can be used in the hot tub. However, we recommend first testing it in a hidden patch of the tub to make sure that the surface is not being damaged. You never know if you don’t accidentally add too much and end up with high pH.


A hot tub may be a luxury, but it’s also an investment. Owning and maintaining a hot tub is a huge responsibility, but who would argue that it has its merits? The next time you have a long day at work, you will pat yourself on the back for your functioning tub.

If you want to continue using your hot tub for many years to come, make sure to test it and perform routine maintenance as often as needed. Simply follow the steps above & don’t be intimidated — you’re just a few steps away from the best bath of your life!