How Long To Wait After Shocking Your Hot Tub (and Why It Matters)

Jennifer Rhodes

By Jennifer Rhodes · Updated

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Every time you use your spa (or once a week if you use it less frequently than that) you need to use what’s called a shock treatment. This is what allows your bromine or chlorine sanitizer to work properly.

It's an essential part of the sanitation process—but it's also important that you don't use the spa too soon afterwards, as this could lead to skin or eye irritation.

So, how long should you wait after adding shock before using the hot tub? We'll get to that in just a second!

What is hot tub shock and how does it work?

Hot tub shock is a chemical treatment that is used in conjunction with your sanitizer to remove contaminants such as oils, lotions and sweat from the water.

There are two different types of shock: chlorine and non-chlorine. You can actually use either regardless of the main sanitizer in your spa. This means that even if you have a bromine system, you can still use chlorine shock.

How it works is that when pollutants or tiny particles of dirt are introduced to the water, your sanitizer will bind to these particles. Eventually, all of your sanitizer will be used up, attaching itself to these dirt particles.

At this point, you need to add shock. What this does is kill all the bad stuff that your sanitizer has bound itself to, which then releases the sanitizer so it can be useful again.

How long to wait after adding shock to a hot tub

Shock is a critical part of keeping your hot tub clean and safe to use. However, it's important to wait a certain amount of time after adding it before using the tub.

As a general rule, you should wait at least 20-30 minutes after adding shock before using the hot tub. This will give the chemical time to do its job without putting you at risk. Ideally, test the water before entering if you plan to use the spa soon after adding shock.

The sanitizer can reach a very high level immediately after shock is added, so that's why you need to wait for the levels to drop before it's safe to use.

Why should you wait to use a hot tub after adding shock?

It's important to wait after adding shock to a hot tub before using it to allow your sanitizer time to dissipate and reach a safe level for use—as well as to kill any contaminants.

Be sure to follow the directions on the shock product you're using, and always err on the side of caution by waiting at least 20 minutes before using the hot tub after shocking it.

What happens if you use a hot tub too soon after adding shock?

If you add shock and then use the tub immediately, you run the risk of irritating your skin and eyes. The levels of sanitizer will peak a few minutes after the shock is added, and then gradually return to a safe level.

But this isn't the only reason; you also need to give the shock time to work. If you use the tub too soon, not only could the sanitizer be at dangerously high levels, but the bacteria and contaminants could still be present in the water.

It's also important to leave the cover off for 30 minutes after you add shock to allow the chemical vapors to escape. You need to give shock time to dissipate in order to avoid damage to your spa.

Closing thoughts

If you are adding shock to a hot tub that is otherwise filled with water and ready to go, you will need to wait at least 20 minutes before using the hot tub. This will give the shock time to circulate and work properly.

Getting in the hot tub straight away could lead to possible skin irritation, redness, and burning—plus the shock will not have had enough time to do its job which is to kill any bacteria present.

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