How Often Should You Shock a Hot Tub?

Truth be told, hot tub sanitizers alone aren’t enough to keep the water in a sanitary condition. That’s because they break down and need to be reactivated with hot tub shock. But how often should you shock a hot tub?

Having owned 4 of them for over 15 years, here’s what I know:

The process of shocking a hot tub should be done on a weekly basis. However, the water can be shocked more frequently if the hot tub regularly sees more than 2-3 people soaking more than 3-4 days per week.

So once a week is what I do.

But then if my daughters have sleepovers and my hot tub is filled with teenage girls for a few hours, I always shock it the next day. That helps combat all the perfumes, skincare products, and lotions that likely washed off into my hot tub’s water.

Read on to discover more on what’s involved in shocking and how best to go about it.

What does shocking a hot tub do?

Shocking a hot tub reactivates the chlorine or bromine sanitizer previously added which, over time, converts to chloramines or bromamines and is no longer able to sanitize the water.

And shock simply means applying a substantial quantity of chlorine (sodium dichlor) or non-chlorine shock (potassium monopersulfate or MPS) to the water. 

When it’s applied correctly, the quality of the water is restored to a healthy state. In simple terms, shocking helps to cleanse the water. I’ll explain how.

After shocking it, the water is now clear, clean, and safe.

Shocking is a vital part of taking care of your tub because, over time, the residues of sweat, urine, oil, cosmetics, pollen, dust, and microbes inhibit the efficacy of the sanitizers you’ve applied.

Before they’re applied, your hot tub water may be smelly, cloudy, or foamy.

And, the mixture of the remnants of contaminants and sanitizers for chloramines or bromamines. Shocking breaks the bond releasing the sanitizers, making them more active and hence effective.

The chlorine shock is much more powerful than the sanitizer (even if the sanitizer is chlorine-based).

The shock reactivates the chlorine and bromine because, as I hinted earlier, the contaminants bind with them, releasing chloramines or bromamines, which are harmful.

These can affect the water chemistry such that you get a false reading when you use test strips! Chloramines give off a foul odor, can irritate the eyes and the mucous membrane.

Now, shocking a hot tub doesn’t imply that you’d no longer need to apply sanitizers regularly. Hot tub shocks are oxidizers, not sanitizers.

You’ll still need to use sanitizers. It’s just that you’ll need to test the water before you apply them and before you shock the water.

In a nutshell, shocking reactivates chlorine or bromine, removes organic contaminants, kills bacteria, and removes chloramines or bromamines.

One question that’s probably on your mind is, can I use a chlorine shock in a bromine spa? That’s what I explored in a recent article of mine. In it, I showed that you could and shared what to do.

 Just click the link to read it on my site.

Can I use shock and chlorine sanitizer at the same time?

Adding both chlorine shock and chlorine sanitizer at the same time is unnecessary and wasteful. What the shock does is to restore the sanitizer’s cleaning capabilities, so adding it at the same time will not do much other than possibly over-chlorinate the water.

So shock should be added at least 5 days after the sanitizer was added.

As we’ve seen in a section above, contaminants weaken the effectiveness of sanitizers over time. You may even get a false reading when you use test strips to gauge their levels.

This presupposes that it’s ideal to apply sanitizers first (and separately).

Then you use the tub after confirming that it’s safe for use. It’s after a few days that you test again and then apply shock to the water.

In the right sequence and the right quantity, the chemicals are incredibly helpful, but they become dangerous when overused. As you know, one can have too much of a good thing.

What if your hot tub is bromine-based? Can you use a chlorine-based shock?

In a recent article, I showed that it’s actually okay to use a chlorine-based shock, and I shared what to do and what to avoid.

Just click the link to read it on my site.

How long do you have to wait to get in a hot tub after you shock it?

Always wait 20 minutes after adding shock to a hot tub before entering the water. Use the jets after adding the shock to help dissipate it into the water, and always check the levels with a test strip before entering.

Ideally, you’ll even have to test the level of the sanitizers before you shock the water. If the levels are low, you’ll add a lot, and you’ll add a lot less if the levels of the sanitizers are high.

Test, test, test… It’s not safe to use the tub unless the levels are ideal based on the recommendation on how to use the sanitizers.

After all, you’re in a soup of chemicals while chilling in a hot tub, so you want to get the level right after sanitizing or shocking.

You’ll also want to know how soon you could get into your hot tub after sanitizing it with chlorine or bromine, right? I answered the question in a recent article of mine in which I shared the ideal time-frames.

Just click that link to read it on my site.

Can you over-shock a hot tub?

Adding more than ¼ cup of chlorine shock to a hot tub weekly risks over-shocking it. That can produce dangerously high levels of chlorine that will need to be lowered before it is safe to soak in.

But you may need to shock it more frequently than someone who uses theirs sparingly.

While I usually do shock mine once a week, as I mentioned above, if my teen daughters have sleepovers and the hot tub is full of teenage girls for hours on end, you can bet I’m shocking it right after they get out, in addition to my weekly shock.

But the scientific approach is best. Simply test the water before you use it so that it’s clean and safe for use.

You may also choose to be proactive: test and shock after heavy use so that you rest assured it’s in a sanitary state before the next use.

If the chemicals are essentially cleansing agents, what’s there to be worried about when the tub has a high level of chlorine, for example?

This is what I explored in a recent article of mine, where I shared the potential negative effects. So, above a certain level, it’s not safe.

Just click that link to read it on my site.

How many times can you shock a hot tub?

Ideally, shock a hot tub once a week if 2-3 people use the hot tub 3-4 times per week. However, it’s always a good idea to shock a hot tub following extra heavy soaking activity or larger numbers of people.

Compared to a situation where you only use it now and then.

The important thing is to always use test strips before you shock the tub. The purpose is to reactivate the sanitizers so that they become more effective.

So, if the tests show they’re still working well, you’ll want to wait a bit and then check again. It’s possible to over-shock the tub, so you always want to conduct tests. It’s the best guide to knowing how many times you can shock a hot tub.

Earlier I mentioned two sanitizers: chlorine and bromine. I bet you’ll like to know when each is ideal and their differences. A recent article of mine goes into some detail about both.

Just click the link to read it on my site.


Keeping a hot tub in the most sanitary condition takes a bit of work. But it’s not rocket science. In this article, we checked out what shocking a hot tub is about (hint: it’s got nothing to do with electricity).

We explored its effect and what happens to the sanitizers you’ve applied before. We considered whether it’s okay to shock and sanitize at the same time. 

We looked at how long you’ve got to wait to use your tub after shocking. 

And, we called it a wrap by looking at how often can you shock your hot tub.

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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