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  • Writer's pictureAqua Warehouse

What is a Hot Tub Shock and What Items do you Need to Do it for the First Time?

Updated: Jan 4, 2023

Shocking your hot tub is a great regular practice to remove contaminants. Many don't remember to do this, and it causes health problems or damage skin cells due to bacteria growth. Shocking your hot tub water is a no brainer, especially when it undergoes heavy usage.

It is essential to shock your hot tub with the right hot tub chemicals on a regular basis to kill bacteria, get rid of cloudy water and eliminate other organic waste.

You can carry out a hot tub/spa shock in many ways. There are chemicals designed for this and information on how to use them, such as; the amounts to use, how many gallons to use, the product to choose, brand/manufacturer, effectiveness, the correct level of chemical balance, etc.

We have uncovered the step of doing a spa shock in easy ways, which provide clarity.

There is no hard and fast rule to it, but our instructions for hot tub care kill bacteria, make your hot tub water quality better, balance the PH levels, tell you the right hot tub chemical to use, and the many benefits attached to shocking your hot tub.

What Does Shocking A Hot Tub Mean?

Shock dosing your hot tub water is the process of adding a higher than normal dose of oxidiser to the spa water. This is called oxidizing. Pool water needs to be shocked within specific periods, likewise hot tubs and spas.

Shock treatment is recommended because it has plenty of benefits. After sanitizing with chlorine, the granules destroy microbes and other organic waste.

These granules then form what is known as chloramines. In simple terms, chloramines are unreactive chemical particles that float on your pool/hot tub surface. These chloramines need to be disabled to circulate; that's where shocking comes in.

Shocking helps remove organic compounds, activate the chloramines and boost the amount of free chlorine circulation in your pool/tub, which improves water quality and easily gets rid of germs.

Why Do You Need To Shock Your Hot Tub?

We all love to be in our bathers (swimsuits) and have a good soak in a hot tub, but unfortunately, bacteria like soaking in hot tubs. They multiply in water and are harmful to our skin and health. It is essential to have them removed by adding hot tub chemicals to shock your hot tub and increase the free chlorine level.

There are many benefits of shock treatment. Some include:

  • Prevent bacteria growth and kills bacteria.

  • Activates free chlorine, which increases the circulation level.

  • Remove slime builds are caused by shampoo and other organic contaminants.

  • Removal of cloudy water is replaced by clean, clear water, etc.

Removing Organic Contaminants Like Chloramines and Bromamines

Amongst the benefits listed, this is one of the most important. You might ask, "how important is it to remove organic contaminants by spa shock?

Imagine walking past a pool, and you can perceive the strong smell of chemicals. Of course, you think that a sanitizer has been used and the pool is clean, right?

It could indicate that the water is still contaminated, and there is a need for the pool to undergo a shock, depending on the chlorine or bromine level. A good explanation for this is that large granules of chlorine and bromine are still floating.

To further explain, these granules float due to the organic waste they have destroyed. Add chemicals to break them so they can breathe and keep the pools or tub clean. It's good practice to shock your hot tub after sanitizing, as it makes the hot tub water clean and helps maintain a correct PH level.

Eradicate Bacterias

Eradication of bacteria is important in pools or hot tubs with heavy use and heavy bather load, which increase the likelihood of spa water contamination.

An average hot tub holds up to seven people, and it is not enough to disinfect or sanitize because the harmful germs that live in these pools would still not be removed. If hot tub cleaning has not happened for a long period, it can create a breeding ground for algae, slime and other microbes.

These bacteria that live on the surfaces of the hot tubs can create worries for illness, irritate children and pets, etc. This means that you should ensure to keep them at bay. Some of the bacteria that can thrive in a hot tub that has not undergone shock treatment are:

  • Legionella: This bacteria thrives in slimy parts of a hot tub, pool, or large water body. It gains contact through the eyes, skin and nose and directly infects the respiratory systems. It makes you sick by inflaming the lungs and is regarded as a severe form of pneumonia, which leads to death in some cases.

  • Crypto is a bacteria that is strong enough to adjust inside the water that has been sanitized. It causes diarrhoea, and its infection cycle lasts about three weeks.

  • Pseudomonas live in slime and algae infested places. They gain access by coming in contact with the skin, eyes and nose and can cause swimmers' ear and hot tub rash.

These bacteria are strong enough to live in an already sanitized pool or hot tub. It is enough to use shock treatment to kill bacteria and maintain high sanitizer levels.

When Do I Need to Shock Dose My Hot Tub?

Shock dosing a hot tub needs to be done weekly or bi-weekly, depending on the size of the hot tub/spa/pool, the number of users who use it, and how often they soak/wash in the hot tub. Incorporating shock treatment into your routine reduces the effect of harmful organic matter, and you'll enjoy it in the long run.

Do I Need To Shock My Hot Tub Before First Use?

Before first use, a hot tub manufacturer would always recommend shocking a hot tub with proper hot tub chemicals. It helps remove resident organic compounds, reduce algae buildup, disinfect it, ensure the PH balance is completely restored, and clean it for first use.

Should I Shock My Hot Tub After Every Use?

Shocking after every use is unnecessary, but it depends on how much it is used and how many bathers use it. Ideally, once a week is perfect. If many users visit it, then twice a week is recommended.

Should I Shock My Hot Tub After Refilling?

Running a hot tub/spa shock is required after a water refill. You can use a dichlor solution, the most common chemical for chlorine shock treatment.

There is also another chemical solution called biguanide. You also need to read instructions carefully and wear safety gloves to protect your hands and goggles for your eyes when handling these chemicals if they accidentally spill.

Measure the chemicals you want to use, and follow the instructions on the container label before you carefully add them into the water. Additionally, remember to use a circulation pump or blower with strong winds for proper air circulation to widely disperse chemicals around the pool of water.

How Do I Know When To Re-shock My Hot Tub?

When hair, shampoo, sunscreen, face products and other organic matter start accumulating in your hot tub, it is due for a shock treatment. Another factor is if animals visit the hot tub regularly. Ensure that the shock dose should be at least once a week so that the drain won't fill with debris and growth of microbes would be regulated.

Add spa shock to your hot tub cleaning routine to disinfect on a regular basis. Also, use a PH dip stick to constantly checkout your water balance. Consult a plumber immediately you notice signs of imbalance. Customer support of plumbing companies would also be willing to help when you reach out to them on their page.

What Are The Different Types of Hot Tub Shock?

Before you purchase a sanitizer and shocking chemical, reading all the information and main types of hot tub shocks is important. You can consult your local plumber and ask for recommendations.

Without having to wait for your plumber, we have curated some important things based on how to manage hot tub shocks, like the safe products, accessories, process, time spent, water type, test to perform, etc.

Knowing these things would help you know the right items and method to use for your hot tub when next it needs a shock. Read the below information to know the different categories of shock chemicals to use.

Dichlor Shock (Chlorine)

Dichlor is one of the most common chlorine compounds used as a sanitizer. Though it can reduce the level of free chlorine, so you'll still need a chemical for a shock dose. Calcium hypochlorite, used for shocking pools, is not compatible with dichlor, as it can explode.

You need to add water to dichlor before adding it to your hot tub or pool, or you can add it raw since it dissolves easily. Moving on, experts recommend trichlor over dichlor. This is because trichlor is less explosive and inexpensive compared to dichlor.

Non-Chlorine Shock

Non-chlorine shock is added after using chlorine or bromine sanitizer. A great example of non-chlorine shock is potassium monopersulfate. Note that while chlorine and bromine can work as a sanitizer and oxidizer, the effectiveness is reduced, and it requires high dosages to do the job, which costs more time and money.

Potassium monopersulfate saves cost, makes water clean and clear, and gets rid of organic compounds in seconds.

Read the label, learn and understand the instructions carefully to be safe. Note that non-chlorine shock still needs to depend on chlorine or bromine to sanitize the pool. You should wear gloves and other safety apparatus to maintain important steps to use safely.

Lithium Hypochlorite

This chemical is ideal for shock treatment and is usually in the form of granules. It contains about 35% chlorine, has a high solubility, keeps PH levels regulated and is suitable for spa/pool/hot tub floors with vinyl cover.

Calcium Hypochlorite

If you have a pool or hot tub and are used to shock treatments, you'd know this chemical from its package, having made a purchase from a shop before or online order. Even if you've not heard of it before, this product works based on the reaction of lime with chlorine gas.

It has the necessary amounts of chlorine needed and activates free chlorine. It works by breaking bonds of organic compounds and the chemical chains that link them together. It is ready-made, safe and costs a decent amount.

However, heat is known to cause weaknesses in its reactiveness, so it's best used at night.

What Is The Best Shock Treatment For Hot Tubs?

As explained before, shocking your hot tub is done in different ways. Knowing the shock dose for your spa shock is essential and maintaining the sanitizer level. There are different shock treatments and shock dosing for shocking different pools/spa/hot tub, water type for the water body involved, etc.

The best hot tub shock to use is dichlor. Dichlor withstands the heat of the hot tubs as long as you leave it open and is not used during the day if the hot tub is outdoors. This is because the sun dries up chlorine easily.

The second best hot tub shock is a non-chlorine shock used with fluorine or chlorine sanitizer. Testing should ensure that the chlorine level is stable and not below 1 million ppm.

How To Decide Which Hot Tub Shock To Use?

Deciding on the hot tub shock mix can make you agitated, especially when the chemicals don't agree. The key to getting the right shock lies in the sanitizer you use. We will explain how sanitizer can affect the type of shock used in shocking your hot tub.

Another important factor when deciding what type of hot tub shock to use is if you make regular use of the hot tub, if animals join in the hot tub soak, or if visitors join and how long they're visiting and will use it. You can quickly decide on the supposed shock treatment when you've got these details.

Chlorine Shock

Chlorine shock dose can be used when chlorine sanitizer is used. Even if you use bromine, fluorine or minerals as a sanitizer, chlorine shock is highly recommended to kill bacteria, dispose of organic compounds, remove smell and maintain safe chlorine levels. It is important to test for chlorine levels, PH levels and other essential checks to keep the spa water clean.

Also, chlorine shock is best when you make heavy use of your hot tub. Make sure not to pull the hot tub cover over the hot tub while it's still undergoing shock treatment. You can wait and cover it after the spa shock is over.

Chlorine Granules and Chlorine Tablets

Both forms of chlorine are ideal, though chlorine granules dissolve faster than tablets. Ensure to check the product bottle and follow the order on how you should use it.

How Much Chlorine Do I Need To Shock A Hot Tub?

The ideal chlorine level is 1 million-3 million ppm. A test can quickly be carried out to check if the levels are good enough to prevent a chemical imbalance. Cloudy water indicates that your hot tub water is not clean enough.

However, after the chlorine shock treatment, the water should become clean and clear. Your hot tub water's standard chlorine shock measurement is 35g of chlorine per 1500 litres.


Bromine tablets or granules are mainly used as a sanitizer for pools or hot tubs


Can I Use Chlorine and Bromine Shock Together?

It is ideal to use a bromine sanitizer and chlorine shock together, as they complement each other and keep the hot tub water clear of impurities.


Biguanide should not be used with any other products, as it can cause a very explosive reaction. To do a biguanide shock, you need to ensure that the chlorine levels are zero because they do not work correctly with chlorine. A store that sells biguanide products sells both the shock and sanitizer so that you can use them together.

There are other shocks like minerals, saltwater, ionizers, etc. You can add them to chlorine or bromine sanitizers based on if they have easy interaction with each other.

How To Shock Your Hot Tub?

Before we continue, below are a list of items you'll need in no particular order:

Items You'll Need

  • Bottle of hot tub shock.

  • Chemical-resistant measuring cups.

  • Test strips.

  • Chemical-resistant gloves.

  • Safety goggles.

  • Circulation pumps for proper air circulation.

  • Step-by-step guide

  • Leave the hot tub uncovered for the duration of the shock treatment. This is to ensure that the hot tub can release gas.

  • Carry out the categories of water tests needed to make sure all levels are in order. PH level 7.4 to 7.6 means that it is ready for shocking.

  • Turn off the blower air jets to ensure that the water isn't too disturbed, but leave the water jets running.

  • In addition to wearing gloves and goggles, also wear protective clothing.

  • Measure your shock chemicals according to the prescribed measurements and carefully add them to the hot tub.

  • Leave uncovered for about 30 minutes to 2 hours to allow full circulation of the chemicals.

  • Chlorine Shock Treatment For the chlorine shock treatment, we suggest using it after very heavy spa use, or after a fresh water change to bring the chlorine level higher. To apply a chlorine shock dose, it’s wise to wait until the end of the day, so that chlorine can work unhindered by sunlight. We also advised to apply chlorine shock after heavy rain, if your spa has had a lot of use, and especially when you first spot signs algae creeping in. Chlorine shock is also sometimes a useful fix for dealing with cloudy water. Applying chlorine shock should become a part of your regular spa maintenance checklist. We recommend using the Aqua Sparkle Rapid Shock for an effective treatment. Please note: Chlorine levels after a shock dosing (sometimes called 'super-chlorination') are extremely high and as such bathing should not be allowed until the chlorine has returned to safe levels, as indicated on your test strips. After any dosing of any chemicals, please always test prior to bathing.

  • Non Chlorine Shock Treatment A non-chlorine shock does not disinfect the water. Its main use is a weekly treatment to oxidise the water, clear hot tub cloudy water and help remove contaminants. The non-chlorine shock will help your chlorine work better by creating ‘Free chlorine’ which is the type of chlorine needed to kill bacteria.

If you’re looking for a chlorine free shock treatment, we recommend using the YourSpa Non-Chlorine Shock Treatment. This product will also help those on bromine to activate the bromine and help it work more effectively.

Both types of shock treatment have their own benefits and weaknesses. We would recommend a combination of the two, however, this can be different depending on your water type or regular bathing routine. If you would like more information on the best hot tub accessories to manage your spa water quality, visit our website today.

When Is It Safe For A Soak After Shocking?

Depending on the shock used, it can be between an hour, six hours or even overnight; so far, the shocking process is complete, and all levels are completely restored.

Check pH Level After Shock.

Before using the hot tub after shocking, use test strips or test kits; the PH level should have returned to 7.4 or 7.6 before use.

How Often Should I Shock My Hot Tub?

Ideally, weekly or every two weeks, depending on the usage level. As a hot tub expert, Aqua Warehouse advises its customers to shock their hot tub water once a week as part of their regular hot tub maintenance. This will help control bacterial growth and destroy any and all bather impurities.

Can You Over Shock A Hot Tub

Yes! However, proper usage of chemicals and proper timing help to prevent that from happening.


Hot tubs require a shock dose at least every week. Doing this ensures that it does not fill up with organic matter, which is harmful.

Frequently Asked Questions

Does shock raise pH?

Yes, it does, and that's why it is required to stay for a while so that chemicals can be fully dispersed and settle.

Can shocking my hot tub lower pH?




Jess Court

I'm Aqua Warehouse Groups Marketing Officer - overseeing all things news worthy in the hot tub industry, with tips and tricks that are bound to make a splash.

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