Do I Really Need to Shock My Hot Tub? (Yes, here’s how often)

Sanitizer is essential for keeping hot tub water clean. But a lot of people are unsure of what hot tub oxidizers, also called shock, do, and wonder “do I really need to shock my hot tub?”

After owning 4 hot tubs, I know that:

Shocking a hot tub must be done to ensure the water is safe to soak in. Plan to add shock once a week, using either chlorine or non-chlorine shock with either chlorine or bromine sanitizer. Not shocking the hot tub can lead to chloramines or bromamines building up which can give false readings on test strips.

Chlorine shock does a better job of cleaning the water than non-chlorine shock. But some people find it too harsh on the skin. 

My personal preference is bromine sanitizer tablets in a floater and powdered chlorine shock.

So, you have a new hot tub and it is nice and relaxing, not to mention very warm in the winter. If you are using your hot tub a lot, or plan to, you should probably learn how to shock it. Shocking is important to help with cleaning your hot tub.

When you use your hot tub, dead skin, hair, and other biological particles end up in there. Eventually, it will build up and make the hot tub nasty. So, it is important to make sure you shock it at least once a week. But what is shocking compared to sanitizing and isn’t that the same thing?

Read below to learn more about the benefits of shocking your hot tub!

Should I Shock My Hot Tub?

All hot tub owners need to shock their hot tub once a week. Additional shock can also be added after extra heavy use. Shock both revitalizes the sanitizer in the water, but it also removes chloramines or bromamines which can render the sanitizer inert.

So the important thing is to shock your hot tub to keep it clean.

Why should you shock your hot tub? A few of the most important reasons are listed below:

  • It helps keep your hot tub water clean.
  • It prevents the water from getting cloudy and murky looking.
  • It removes any organic materials in the water.
  • It gets rid of any non-bacteria in the water.
  • It gets rid of the chloramines and bromamines from sanitizing your hot tub.

It is important to shock your hot tub consistently and to also keep it nice and sanitized.

Without this, the water can get gross and murky looking, and no one will want to use the hot tub. It may also damage the hot tub itself if left sitting long term. You need to make sure your hot tub is clean for use whenever you are done with it for the day.

Unsure of the difference between sanitizing and oxidizing?

Both a good sanitizer and a good oxidizer are crucial for the water quality of your hot tub. But they are are also essential for the safety of everyone soaking in the hot tub.

If you want to know the difference between using oxidizers and sanitizers check out this recent article. I get into all the differences and whether or not it’s OK to use a chlorine oxidizer and a bromine sanitizer.

Just click that link to read it on my site.

What Does Shocking a Hot Tub Do?

Shocking a hot tub revitalizes the sanitizer in the water which, over time, becomes less effective as it destroys contaminants. Chlorine breaks down into chloramines and bromine breaks down into bromamines, both of which can give false test readings for sanitizer levels.

And if you think the sanitizer levels are good when they really aren’t, that’s not safe to soak in!

After shocking with chlorine, it will convert the chloramines back to active chlorine or if you use bromine sanitizer, it will convert the bromamines back to bromine.

This way it will start sanitizing again for you. However, if you use bromine to sanitize, and you use a non-chlorine shock, then the bromide ions get activated. But these ions have no cleansing powers.

Want to know if you can use chlorine to shock a bromine hot tub?

Luckily, I answer that question, with all the pros and cons, in this recent article. In the end, it does not matter which shock treatment you go with; they both eventually do the same thing.

They clean your hot tub, keep the water nice and sanitized, and they allow your hot tub to remain warm and toasty during those cold winter nights.

What the Difference Between Shocking a Hot Tub and Sanitizing It?

There are many ways to sanitize and shock your hot tub.

But what is the difference between the two? Well, when you shock a hot tub, you are removing organic matter from the water and reactivating the sanitizer. Whereas sanitizing removes just bacteria and viruses. Therefore, it is important to do both for your hot tub, to keep it clean and working properly.

What do you use or not use to shock versus sanitize? Read below to find out more!


  • Calcium Hypochlorite
    • Cal hypo is cheaper and easier to find.
    • It is unstabilized chlorine.
    • Not good for the heat from hot tubs.
    • It contains calcium which will damage your hot tub.
  • Dichlor shock
    • The most active ingredient in many hot tub shock formulas.
    • It can be added right into the water, depending on the instructions on your package.
    • It is stabilized and will be okay in the heat.
    • Make sure you shock at night, so the sun does not overheat the hot tub water.
  • Lithium Hypochlorite
    • Harder to find.
    • Lithium is usually reserved for batteries.
    • Very expensive if you do find it.
    • Not worth using compared to dichlor.
  • Non-Chlorine Shock
    • Will not kill bacteria.
    • It is usually effective as an oxidizer.
    • You can alternative between weekly or biweekly chlorine treatments, then use non-chlorine more often.
    • As an oxidizer, it will help to get rid of any biological debris.

Lots of people think that if you can sanitize a hot tub with chlorine, then inexpensive liquid bleach should work too.

Unfortunately, they’re not 100% correct. While you can use liquid bleach in a hot tub, you must use it in a certain way. So make sure you read this recent article before pouring in the Chlorox.

Just click that link to read it on my site.


However, with sanitizing, which is also a good thing to do, you just need to use either chlorine or bromine.

Either one is great for cleaning or sanitizing it. However, chlorine is not great in the heat of your hot tub and breaks down faster. So while it’s cheaper, you will find you are adding it more frequently.

Bromine is better to use overall as it holds up to the heat better. It also is easier on the skin and has less of a chlorine odor.

It may be a good idea to use an Ozonator to sanitize your water too!

But Ozone generators do have both their pros and cons.  They also have to be attached, although the average homeowner can definitely do the work needed.

Check out this recent article to see if an Ozonator makes sense for you. Just click that link to read it on my site.

How Often Should I Shock My Hot Tub?

Plan to add shock to a hot tub once per week. However, if a lot of people use the hot tub frequently, then it may need to be shocked twice per week.

I like to check the water chemistry before every soak.

Then unless it’s way off, I like to adjust the chemicals when I get out. That way, it’s ready for next time. Then, at the end of each week, I’ll add some shock.

Sunlight can rob some of the chemicals of their power. So for that reason, I like to keep the lid closed after adding any hot tub chemicals.

How much shock do I need for a 400-gallon hot tub?

For a four-hundred-gallon hot tub, plan to add approximately 1/8 cup of hot tub shock each week.

But truth be told, I usually eyeball my chemicals. I probably start with about half a quarter cup. Then I let it work for about 30 minutes (with the jets on) and test again.

But remember. You can always add more. If you add too much, you’ll have no choice but to wait it out until the levels drop.

Did I cover all you wanted to know about whether shocking a hot tub is required?

In the end, shocking your hot tub is practically “law” when it comes to owning a hot tub.

All hot tub owners shock and sanitize their water and make sure that the water is clean. No one wants to sit in murky, cloudy water! And with shocking, you need to ensure you do it about once per week.

Personally, I like a powdered chlorine shock with liquid bromine for my sanitizer.

Also, make sure you’re checking and adjusting the pH and alkalinity as needed. Those are also vital for the water quality, longevity of your equipment, and the health of those soaking in it.

Jeff Campbell

Jeff Campbell is a husband, father, martial artist, budget-master, Disney-addict, musician, hot tub lover, and recovering foodie having spent over 2 decades as a leader for Whole Foods Market.

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