How to Lower Alkalinity in Hot Tub: A Guide to Hot Tub Water pH

Nothing is more luxurious and relaxing than soaking in a tub’s bubbles and hot water after a stressful day at work.

However, you can’t just take a dip any time you feel like it. Owning a hot tub also requires proper upkeep.

One of the most crucial tasks of maintaining a hot tub is ensuring the correct chemical composition of the water.

One chemical aspect you need to keep an eye on is how to lower alkalinity in hot tubs and keep it well-balanced.

how to lower alkalinity in hot tub

What Is pH?

The pH or power of hydrogen is the hydrogen ion concentration in the water that determines if it’s considered basic, acidic, or neutral.

An acidic water level ranges from 0 to 7, while 7 is neutral, and 7 to 14 pH is deemed basic.

That said, your hot tub water should have a pH ranging from 7.4 to 7.6.

As it is, anything can change the pH level of the water in your hot tub, especially if the alkalinity level is incorrect.

Similar to unbalanced alkalinity, if the pH level is beyond the ideal range, it can corrode the metal parts of the tub.

What Is Alkalinity?

Alkalinity is the amount of dissolved alkaline substances found in water that helps neutralize the acid.

It is also called the buffer since it helps balance the pH level in your hot tub water and resist extreme changes.

Ideally, the total alkalinity range of your hot tub water should be around 80 to 120 parts per million (PPM).

An unbalanced alkalinity level in your hot tub may have an unfavorable effect on the water’s appearance. It may also cause skin dryness.

How Can Incorrect Alkalinity Level Affect the Hot Tub Water?

High or low alkalinity levels harm your spa and your skin, and the low range is riskier between these two.

When the alkaline level is low, it will be hard for the water to neutralize the acids, causing rapid pH changes and turning it green.

Keeping the alkaline at a low level can cause corrosion on your hot tub’s internal equipment, negatively affecting its surface.

Besides turning the water green, a high alkaline level can lessen the effectiveness of your water sanitizer, increasing the pH level.

High pH levels can cause calcium build-up, scale formation, and cloudy water. The yellowish flakes on the water from calcium can impact the jet’s performance and equipment negatively.

You will need to deep clean the hot tub to remove mineral deposits and prevent further damage.

What Causes High Alkalinity?

Most hot tub owners conduct regular draining and cleaning of their spas every three to four months to prevent any build-up.

However, there are still other causes for the increase in the alkaline level of your hot tub water, including the following:

Human Error

Sometimes, you may cause a high alkaline level in your hot tub water if you have added too much baking soda or alkalinity increaser.

Sweat and Other Body Stuff

You might have forgotten to take a shower in your excitement to jump right into the hot, bubbling water of your spa.

Body lotions, hair gels, perfumes, sunblocks, and other things you use on your body can increase the alkaline level when mixed with hot tub water.

Too Many Chemicals

In your quest to have well-balanced water in your hot tub, you might be adding too many chemicals without realizing it.

You can prevent this issue by draining and cleaning the hot tub quarterly or every three to four months.

Water Source

Another reason for the high alkalinity level may be your water source. You may ask for water reading from your local water district so you can make the necessary adjustments.

learn how to lower alkalinity in hot tub

How To Lower Alkalinity in Hot Tubs

One of the quickest ways to reduce the alkalinity in the hot tub water is by adding sodium bisulfate or a pH-decreasing solution.

As mentioned above, alkaline and pH may differ, but they work together to provide well-balanced hot tub water.

Before doing anything, know the water capacity of your hot tub first, then follow the steps below.

1. Hot Tub Water Testing

Know the current alkalinity level of your hot tub water by using a test strip or a liquid test kit before you put anything in your spa.

This way, you will know if you need to lower the alkaline level or not. You should try to reach at least 100 ppm.

2. Add pH Decreaser

Sprinkle about 85 grams or three ounces of sodium bisulfate powder in 1000-gallon hot tub water to lower the alkalinity by 10ppm.

Ensure that the hot tub is running as you sprinkle the ph decreaser powder for quicker and more effective mixing.

Allow the hot tub to circulate for at least 20 minutes before turning it off. The combined acid and water help reduce the total alkalinity and balances the pH level.

3. Retest the Water

Allow the sprinkled sodium bisulfate to dissolve and mix with the water for an hour before retesting.

Leave the hot tub uncovered to allow the water to breathe, release chemical odors, and protect the cover from chemical smell build-up.

Make the necessary adjustments as needed based on the test results.

Repeat the process if the alkalinity level is still high.

Once you have achieved the appropriate alkalinity level, let it rest for 24 hours and do another test to ensure the level is still the same.

How To Lower pH Level Naturally

If you don’t want too many chemicals in your hot tub, you can lower the pH level by using vinegar instead.

Get four cups of regular or apple cider vinegar, turn on the hot tub, and gradually pour it into the circulating water.

After pouring the vinegar, turn off the spa and let it rest for a few hours before testing the water’s pH level.

You can repeat the process until you reach the desired level.

How To Increase Alkalinity in Hot Tubs

Too much pH reducer addition will lower the alkalinity below its appropriate level, requiring you to increase its reading.

You can increase the alkalinity level of the hot tub water by adding the right amount of sodium bicarbonate.

Add 2.25 ounces of sodium bicarbonate for every 1000-gallon of water to help increase alkalinity by 10ppm.

Turn on the spa for 20 minutes as you sprinkle the powder on the tub’s edges before turning it off, allowing it to rest for an hour.

Retest the water, and leave it overnight once you have reached your target alkalinity level.

Repeat the testing the following day to confirm if the reading is still the same.

Which Should You Adjust First?

As you can note from the above information, baking soda or sodium bicarbonate is an alkalinity increaser.

When you use it, and the alkalinity readings are below the recommended levels, increase the alkalinity first.

Retest the water and see if the readings have improved.

If you need to increase the pH level, just add soda ash or sodium bicarbonate.

Maintain the Correct Alkalinity Level of Your Hot Tub

To sum up, there are a few key points you need to remember about how to lower alkalinity in hot tubs and maintain chemical balance.

First is to allow the water to circulate for 20 minutes after adding a chemical before doing another test. For more accurate readings, let the water rest overnight before testing.

The ideal alkalinity range is between 80 and 120 ppm, while a neutral pH level is between 7.4 and 7.6.

Also, add chemicals with 15 minutes intervals, allowing it to rest without cover. Lastly, change the hot tub water quarterly.

If you want accurate test results, put your water sample in a clean cup, let it cool to room temperature, and use a liquid test kit for precision.