How to Shock A Hot Tub: Tips for Successful Treatment

Michael Keenan


Hot Tub Water Chemistry

Are you looking for ways to make sure your hot tub stays clean? Shocking your hot tub is an effective way of sanitizing it by removing any contaminants or impurities. It also helps to activate chlorine and bromine levels in the water so that they can work more effectively as sanitizers.

In this article, I’ll discuss in detail how to shock a hot tub and the different types of shocks available for hot tubs. You’ll also learn about the benefits of shocking a hot tub and some useful tips that you can use to ensure a successful shock treatment process.

So, if you want to keep your hot tub healthy and safe for use, then read on!

how to shock a hot tub

Quick Answer:

Hot tub shocking is the process of adding a large dose of shock compound or oxidizer to hot tub water to clean it. There are two types of shocks commonly used for shocking hot tubs: chlorine-based and non-chlorine-based.

Before using either type, the pH level in the water must be tested first and adjusted if necessary. After pouring the shock into the water, allow it to work for 20 minutes before testing the pH again and then allowing it to work for up to an hour depending on which product you use.

Shocking your hot tub regularly will help remove organic contaminants, kill germs, activate sanitizers more effectively, and prevent health issues.

What Is Hot Tub Shocking?

Adding a large dose of a shock compound or oxidizer to your hot tub water to clean it is known as hot tub shocking. Shocking the water removes any nasty contaminants such as chloramines and bromamines from the water. It also kills bacteria, fungi and germs, plus shocking reactivates the bromides and also clears up cloudy water.

In addition to maintaining the cleanliness of the water, shocking aids the regular sanitizers to fight bacteria build-up effectively, without which the sanitizers may not do their job effectively, leading to potential health and safety issues in the hot tub.

So, whether you use the hot tub frequently or if the hot tub has been unused for a while, it is essential to shock the water before using it.

This is part of my series of articles covering everything you need to know about shocking your hot tub or spa. See also – how often to shock your hot tub. Next up learn if you can over shock a tub and what to do if this happens. Then find out how long you should wait after shocking before using the hot tub again. You’ll be an expert in no time!

Types of Shock Treatments

If you’re confused about what shock treatment you should use for your hot tub, to make things easier for you, I have discussed the different types of shocks available and how to use them.

The two main types of shocks that are commonly used for shocking hot tubs are chlorine-based shocks and non-chlorine-based shocks.

The type of shock you pick will essentially depend on the type of sanitizer that you use to clean your hot tub regularly. Have a look at my guide to alternative sanitizers for some different options available today.

Chlorine-Based Shock

Chlorine-based shocks or dichlor shocks (dichloroisocyanuric acid) are commonly used for shocking hot tubs. These shocks work by increasing the free chlorine levels in the water, which in turn, helps to sanitize the water.

Irrespective of whether you use chlorine or bromine as your hot tub sanitizer, you can use a dichlor shock to sanitize the hot tub water effectively.

Chlorine-based treatments are best for hot tubs that are used quite frequently or ones that have high traffic regularly. Using a chlorine shock is good when you open the hot tub, change the water or want to clean it after a particularly heavy load of bathers.

It is also recommended to use non-chlorine shock in between intermittent chlorine shocks to prevent organic build-up in the hot tub. But you must take care to use chlorine shocks only periodically because the chemicals can take a toll on the plumbing of your hot tub.

spa jets under water in hot tub

Non-Chlorine Based Shock

The second type of shock treatment is a non-chlorine-based shock. These are typically gentler compared to chlorine shocks and will not disinfect the hot tub water by killing the bacteria and germs in it.

Non-chlorine shocks work to clean up the water and remove the contaminants in the water by oxidizing them. They help to activate the free chlorine in the sanitizer and help the sanitizer to work more effectively.

It is recommended to use a non-chlorine shock once in 7-10 days to keep the water in your hot tub clean and sanitized.

Confused about all these different chemicals? Make sure you check out my guide – hot tub chemistry 101. It lists them all!

Preparing to Shock Your Hot Tub

Once you have decided what type of hot tub shock to use, you need to know how to shock your hot tub. And, to make things easier for you, in the next sections, I will give you step-by-step instructions on how to go about the process.

Making Sure it Is Safe to Shock – Testing the Water pH

The first step is to ensure that your hot tub is safe to shock and to do this, you must first test the pH level of the water. You can check the pH level of the water by either using a test liquid or a test strip.

The test will tell you the pH of the water, whether it is alkaline or acidic. Ideally, the pH level of the hot tub water should be between 7.2 to 7.6, if you’re using a chlorine sanitizer.

And if you’re using a bromine sanitizer, then the pH should be between 7.0 to 7.4. If the pH is below or above this range, then you must adjust it before shocking the water.

Preparing the Tub for the Shock Treatment

Remove the cover of your hot tub. This will allow the oxygen to reach the surface of the water. If you have any accessories in the tub, remove them.

Gathering the Supplies Needed

You will need the following supplies:

  • Hot tub shock
  • Gloves
  • Safety goggles
  • Measuring cup
  • pH test strips or test liquid
couple in a hot tub

How to Shock a Hot Tub

Step-By-Step Instructions for Shocking

Here are the step-by-step instructions on how to shock your hot tub:

Prepare Yourself

Before you start the process of shocking the spa, first wear your safety gear such as goggles and gloves to ensure that you are safe when handling the shock chemicals.

If your hot tub is located indoors, then ensure that there is good ventilation in the room before using the shock chemicals by turning on the exhaust fan and/or opening a window.

Turn On the Pump

Turn on the circulation pump of the hot tub. The movement of the water will help to distribute the shock chemicals properly through the hot tub.

But ensure that the hot tub jets are turned off so that the water is circulating but is not too agitated, as this will cause the shock chemicals to dissipate very quickly and prevent it from working properly.

Leave the hot tub uncovered throughout the shocking process to allow the gases produced during the shocking to dissipate quickly.

hot tub with pumps running

Pour the Shock Chemicals Into the Water

Applying the shock treatment to the water is extremely simple. Avoid pouring the shock into the hot tub from the container directly.

Always measure the amount of shock required depending on the amount of water in the hot tub and pour it carefully into the water as per the instructions on the product label.

If you spill any shock accidentally, then clean it immediately and throw it away safely. When not in use, make sure to store the shock safely, out of reach of kids and pets.

Wait for the Shock to Work

Wait for around 20 minutes and allow the shock to do its work. And, during this time, make sure that the hot tub is uncovered to allow the shock to off-gas.

Test the pH of the Water

Typically, after shocking your hot tub, it will be ready for use after around 20 minutes to 1 hour. But it may be a good idea to check the label of the product to find out how long you must wait until it is safe to get back into your hot tub.

Usually, chlorine, as well as non-chlorine shocks, raise the pH levels of the hot tub and so it is recommended to test the pH of the water to ensure that it is neutral before using the hot tub.

Tips to Ensure a Successful Shock Treatment

Use the correct amount of shock required for the amount of water in the hot tub as per the recommended amount on the product label. Using too little of the shock means that the water will not be cleaned effectively and using too much will cause too high levels of chlorine, which means that you will not be able to use the hot tub for a long time.

Make sure that the shock has sufficient time to work in the water before reusing the hot tub. Also, test the water to ensure that it is safe for use before using the hot tub after shocking.

The Benefits of Shocking a Hot Tub

There are many advantages of shocking your hot tub. Let’s take a look at some of them below.

  • It helps to remove organic contaminant build-up including cosmetics, sunscreen lotion, creams, shampoo and dead skin that cause scum or the water in the hot tub to turn cloudy over time.
  • It helps to kill bacteria and germs in the hot tub.
  • Sanitizers such as chlorine or bromine kill bacteria and also remove organic contaminants from the hot tub water and, in turn, produce waste products known as chloramines and bromamines. These wastes cause the water to become smelly. Shocking the hot tub helps to remove the chloramines and bromamines.
  • Shocking the water boosts the chlorine and bromine levels in the water without the need to add more sanitizer, which becomes less effective over time.

Common Questions:

How much chlorine should I add when shocking a hot tub?

When shocking a hot tub, you should add 3-5 pounds of chlorine per 500 gallons of water. This is roughly 1.3kg to 2.2kg per 1892 liters.

Is it safe to shock a hot tub while people are in it?

No, it is not safe to shock a hot tub while people are in it and all people should be out of the water before shocking the hot tub.

How often should I shock my hot tub?

It is recommended that you shock your hot tub at least once a week or more if necessary.

Are there any special safety precautions that must be taken when shocking a hot tub?

Yes, when shocking your hot tub take care to protect yourself and others by wearing safety gear such as eye protection and gloves, and make sure the area is well ventilated.


Hot tub shocking is an important process to maintain the cleanliness of your hot tub, killing bacteria and germs, removing contaminants, and reactivating bromides. Depending on the type of sanitizer used in your hot tub, you can either use chlorine or non-chlorine based shocks.

To ensure a successful shock treatment, make sure to use the correct amount of shock required for the amount of water in the hot tub as per the product label and test the pH level before and after shocking for optimal results.

Shocking your hot tub periodically is an easy and effective way to ensure that the sanitizer is working properly to keep your hot tub clean, hygienic and safe. So, what are you waiting for – give it a go today!

michael keenan author

Author - Michael Keenan

I'm Michael Keenan the owner and creator of the Outdoor Care Guide. I'm a trained horticulturist with over 30 years of experience in pool care, plant care, and landscape care! Seemed like a good idea to share - I think I can make your life easier and save you some time and money!