How to Shock Your Hot Tub or Spa

Have you recently heard the term 'shock dosing your hot tub' and want to learn what it's all about? Then you've come to the right place. We're here to debunk the junk and explain everything you need to know (and more) about shocking your water.

Dive in to discover why you should be carrying out regular shock treatments, the different chemicals available and the safest methods.

Let's begin.

What is a hot tub shock treatment?

In essence, shocking your hot tub or swim spa means adding a higher than usual dose of oxidiser chemicals to the water. This is also known as oxidising.

We advise everyone to shock their water once a week to reduce bacteria and impurities. You can do this with one of two products; chlorine shock or non-chlorine shock.

Why shock my hot tub?

The main reason to shock your hot tub is to clean and clear the water. But it will also:

  1. Kill bacteria – Chlorine-based shock treatments sanitise hot tub water and keep it safe for bathers.
  2. Remove organic contaminants – Standard sanitisers struggle to manage waterborne organic compounds when lots of bathers use a hot tub. But shocking can eliminate these pollutants.
  3. Reactivate sanitisers – Sanitisers (bromine or chlorine) attach themselves to contaminants to become 'used'. But a shock treatment breaks this bond and frees the chlorine particle from the pollutant after leaving it in the filter. This reactivates the chlorine and allows it to keep killing bacteria.

Which type of shock should I use?

Both chlorine and non-chlorine shock have their strengths and weaknesses. But where possible, we recommend combining both treatments – providing your water type and bathing routine permit this.

Chlorine shock

Chlorine Shock

Chlorine treatment is ideal after excessive use or a water change and is an excellent disinfectant. But remember, chlorine shock raises the chlorine level in your hot tub. As such, you'll need to wait for it to reduce naturally before using your spa.

During this time, the cover should remain off for at least 20 minutes while running a regular jet cycle. This will reduce the risk of chemical damage to the tub and any accessories.


Non-chlorine shock

Non Chlorine Shock

Non-chlorine shock won't disinfect water. It's primarily used as a weekly treatment that oxidises, removes contaminants and clears cloudy water. It also helps chlorine to work more efficiently and kill unwanted bacteria.

Did you know: If you use a bromine sanitiser, you can use a chlorine or non-chlorine-based shock treatment. But never mix the dry chemicals, as this can cause a dangerous chemical reaction.

Shop our full range of shock treatments here.

How should I shock my hut tub?

You can easily shock dose your hot tub's water once you know its litreage. Take a peek at our quick how-to guide:

  1. Remove your hot tub's cover so that oxygen can reach the water's surface.
  2. Ensure the pH balance is correct – between 7.2 and 7.6 with a chlorine sanitiser or 7.0 to 7.4 with a bromine sanitiser.
  3. Turn on the jets to aerate the water. If you have a blower, do not switch this on.
  4. Next, please read your chemical's label. Most products require 17g of non-chlorine shock per 1500 litres of water or 35g of chlorine shock per 1500 litres.
  5. Carefully pour the treatment into your spa near the water inlets. This will allow it to circulate evenly.
  6. Wait for at least 20 minutes before using your spa. Please keep the cover off for the duration.

How long do I need to wait after shocking my hot tub?

Hot tub water testing

There is no set time to wait before using your hot tub. All brands give different recommendations, ranging from 20 minutes to 24 hours. However, before donning your swimsuit and stepping inside, we suggest using a test strip to ensure your chlorine levels are safe.

Top tip: Non-chlorine shock treatments don't sanitise the water. This means you can usually use your hot tub after approximately 20 minutes of adding the chemical.

Hot tub chemical safety

Here's how to use hot tub chemicals like a professional:

  • Before use, please read the product's label and follow its instructions.
  • Never mix hot tub chemicals unless instructed to do so by a specialist.
  • Always add chemicals to water, never the other way around.
  • Never add chemicals to your hot tub water while it's in use.
  • Only use hot tub chemicals in well-ventilated areas.
  • If using powdered chemicals, always beware of strong winds.
  • Store chemicals out of reach of children and animals.
  • Wear protective shoes and clothing when handling chemicals.
  • Wash your hands thoroughly after use.
  • Test your hot tub water daily with test strips.
  • Store all chemicals away from heat and moisture.
  • Always leave your hot tub switched on unless changing the filter or water.

Parting advice

And there you have it; our expert guide to shocking your hot tub. Please read the instructions supplied with your chlorine products for more information.

Need more advice? Give us a call on 01482 212322 or email and we’ll help you out. Or drop in and see us in our Hull or Leeds showrooms to see our hot tub chemical range for yourself. 

Not near one of our Yorkshire hot tub showrooms? No problem, if you’re looking for a new hot tub you can explore our virtual showroom or book a video call with our showroom team

Stay up to date with our latest products, hot tub guides and updates on Facebook or Instagram.

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