Hot Tub Shock Treatment: Why It’s Essential for Clean Water




what does shock do for a hot tub

A hot tub is a great addition to any home. It provides relaxation, fun, and even health benefits. But most hot tubs can become a breeding ground for harmful bacteria.

In this article, we will look at the effectiveness of spa shock treatments and why you should consider using them to keep your hot tub safe. 

What is Shock Treatment?

Shock treatment is a process of adding chemicals to your hot tub water to increase the availabilty of free chlorine available to sanitize your tub by breaking down and oxidizing the chloramines or bromamines (if you use bromine to sanitize) in the water. Let me explain…

Why do you need to use hot tub shock?

Whenever you use your hot tub, regardless of how clean you are, you bring into the water body oils, sweat, dead skin cells, body lotions etc. You can’t tell that all of those things are causing a problem but over a period of time as these organic contaminants build up in the water it begins to bind with the chlorine molecules turning it into a chloramine molecule.

When these build up you get that chlorine smell and it ties up the chlorine molecules in the water affecting the chlorine level available to sanitize the water properly.

If you don’t address the problem to get your water clean, your water quality goes down, you might start to get cloudy water and it could even create a build up of algae in the hot tub water.

When to Shock

If you don’t shock on a regular basis then there are a couple of signs that your water requires shocking.

The first is the smell of your hot tub. When you’re adding chlorine to your water to sanitize it there shouldn’t be a strong chlorine odour, like when you walk into a public swimming baths. If that’s what you get when you take off your hot tub cover then that is a good sign that your water has a lot of chloramines in it.

The other sign is when you do your strip test you can’t get your total chlorine and free chlorine to stay at the right levels. If you keep having to add lots of chlorine to get balance there’s a good chance that a shock treatment will make all the difference to your sanitizer levels.

What does shock do for a hot tub?

When your hot tub is full of chlorinated water that is unbalanced, the chlorine particles don’t have enough active chlorine to allow the hot tub chemicals to do their job of keeping your spa water clean and safe.

Shock has the ability to come in like a knight on his shining charger and deal with it quick and easily. It can create a chemical reaction which brings your chlorine level up to break point.

Break point is when the free chlorine gets to 10ppm(parts per million) and then seperates the chlorine from the waste product it has joined with. The waste molecules disappear into the atmosphere leaving your tub water clean. 

SpaGuard Enhanced Spa Shock 6lbs

Multi-Purpose shock 

Restores Spa Water Sparkle and Removes Unpleasant Odors

  • Four functions in one
  • Removes Unpleasant Odors
  • Treat and Soak in as soon as 15 Minutes!

What spa shocks should I use?

There are shocks that kill all bacteria and contaminants. Other types of shock get rid of most contaminants but don’t deal with bacteria. Make sure you choose a that is meant for hot tubs and spas and not a pool shock. So which spa shock should you choose?

Chlorine Shock

Chlorine-based hot tub shock is suitable for tubs sanitized with chlorine, bromine, ozone or saltwater. It should contain the active ingredient “Sodium Dichloro-s-Triazinetrione Dihydrate “. This will kill all bacteria and contaminants. This is the best type of shock to use if you have a heavy bather load to get rid of unwanted bacteria. Use this as part of your regular maintenance routine.

Non-Chlorine Shock

Non-chlorine based shocks don’t kill bacteria or disinfect your water but they will oxidize the water getting rid of organic contaminants and activates free chlorine or free bromine. This is great to use if you don’t use your hot tub often to keep your water clear but if you do use your hot tub daily or more regularly then regular chlorine shocks are better.

Biguanide Shock

If you use a biguanide sanitizer in you hot tub then you will need to use a biguanide shock to clear the water. 
If you’re unsure which is the right one for you, check the manufacturers instructions.

SpaGuard Enhanced Shock

How do you use a spa shock?

Once you’ve purchased your chemical shock you will need a suitable container to mix it in unless it’s in liquid form.

Test you water with a test strip before you start. You need to have the pH levels correct before you start otherwise it won’t work correctly. So fix that if necessary before you add your spa shock.

Remove you spa cover and leave it off while the shock does it’s work, this allows the contaminants to evaporate into the air and not back into the water.

Run the water jets or bubble function throughout the process as this helps to agitate the solution in the water.

Before you mess with chemicals you may want to use some safety gear so the solution doesn’t splash onto your skin or into your eyes.

You need to know how many gallons of water your hot tub holds so that you can use the right amount of shock. If you don’t know you can check with the manufacturer. It’s often in the guide that comes with your spa.

Add your shock solution carefully and let it run for at least 20 minutes or as per the instructions on the container. Then check the water again with your test strip to see what the level of chlorine is now.

Can you get in the hot tub after shock treatment?

If the chlorine levels are now at a safe level- total chlorine between 1-5 ppm and free chlorine between 1-3 ppm then it’s safe for you to use the hot tub. If it’s too high then let it run for a while and keep checking it until it reaches safe levels.

How often do you need to shock a hot tub

You can add it into your weekly maintenance routine to keep water clarity but make sure that you always do your water tests to make sure the sanitizer levels are safe.

Some people find that using a small amount after each use of the hot tub works well for them to keep the tub water clean. You will have to test it out to see which is the best option for your situation.


In conclusion, the main purpose of using a shock water treatment is to keep your spa free from bacteria growth that might be missed by your regular sanitizer.

So whether you’re planning a party, hosting a get together, or just want to relax after a hard day, you can rest assured knowing that your spa will stay clean and safe throughout the entire process.

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