Hot Tub Free Chlorine Low: What You Need To Know

Hot Tub Cleaning Systems, Low Maintenance, & ChlorineFree!


Hot tubs are a great way to relax and unwind after a long day, but they do require some maintenance to keep them clean and safe to use. One of the most important aspects of hot tub maintenance is keeping the free chlorine level within the appropriate range. In this article, we will discuss what free chlorine is, why it is important, and what to do if your hot tub free chlorine level is low.

What is Free Chlorine?

Free chlorine is a chemical compound that is commonly used as a disinfectant in hot tubs and pools. It works by killing bacteria and other microorganisms that can make people sick. Free chlorine exists in two forms: hypochlorous acid (HOCl) and hypochlorite ion (OCl-). Together, these two forms make up the total chlorine level in your hot tub.

Why is Free Chlorine Important?

Free chlorine is important because it helps to keep your hot tub clean and safe to use. When the free chlorine level is too low, bacteria and other microorganisms can grow and thrive in your hot tub, which can lead to illnesses and infections. On the other hand, when the free chlorine level is too high, it can cause skin and eye irritation and even damage your hot tub equipment over time.

What Causes Low Free Chlorine Levels?

There are several factors that can cause low free chlorine levels in your hot tub. One of the most common causes is heavy bather load, which means that there are too many people using the hot tub at once. Other factors that can affect free chlorine levels include temperature, pH balance, and sunlight exposure.

How to Test Free Chlorine Levels

Testing your hot tub free chlorine levels is easy and can be done using a test strip or a liquid test kit. Simply dip the test strip or test kit into the hot tub water and compare the color of the strip or liquid to the corresponding chart to determine the free chlorine level.

What to Do if Free Chlorine Levels are Low

If your hot tub free chlorine level is low, there are several steps you can take to bring it back up to a safe level. First, you should shock your hot tub with a chlorine shock treatment. This will help to kill any bacteria or other microorganisms that may be present in the water. You should also make sure to clean your hot tub filters and adjust the pH balance of the water if necessary.

How to Prevent Low Free Chlorine Levels

The best way to prevent low free chlorine levels in your hot tub is to maintain a regular maintenance schedule. This should include testing the water chemistry regularly, cleaning the filters, and adjusting the pH balance as needed. You should also limit the number of people using the hot tub at once and avoid using oils or lotions in the water, which can interfere with the free chlorine levels.


Keeping your hot tub free chlorine levels within the appropriate range is essential for maintaining a clean and safe hot tub environment. By understanding what free chlorine is, why it is important, and how to test and adjust the levels, you can enjoy your hot tub with peace of mind and relaxation.