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Most pool owners add shock to their swimming pool when the water chemistry is unbalanced. If you’re experiencing bad algae bloom or cloudy water, it’s time to shock the water. 

But how long should it take for the shock to do its job? Can you swim in the pool after adding shock treatment to the water? 

We’ll help you answer all these questions and more. Keep reading, and let us help you keep your pool sparkling clean. 

Can You Swim In A Swimming Pool After You Shock It?

You should wait at least 24 hours after adding pool shock to swim. This is especially true for chlorine shock, since chlorine can be dangerous if inhaled or swallowed in high doses. Since pool shock is a concentrated form of chlorine, this dosage can hurt anyone who swims in or swallows it. 

The safest way to determine if your swimming pool is safe for swimming is to test the chlorine levels. Ideally, chlorine levels are 3 parts per million in the pool water. This is safe for swimming and high enough to kill bacteria and algae. 

Non-chlorine shock is different from chlorine-based pool shock. Non-chlorine shock is not made from chlorine and isn’t as corrosive. While it’s a suitable pool cleaner, it’s less potent than chlorine shock since it’s a weaker chemical. 

However, you can swim in the pool just a few minutes after adding non-chlorinated pool shock. If your swimming pool isn’t particularly dirty or has algae bloom, you might consider using non-chlorinated shock. 

Can You Add Chlorine and Shock to the Pool at the Same Time? 

Chlorine and shock should not be added at the same time. Adding pool shock and pool chlorine together can cause the two to cancel each other out and thus cause both to do nothing. 

Pool shock does not contain chlorine stabilizers, which is why most shock treatment companies advise you to add it at night. The sun’s UV rays can dissolve the molecular bond of chlorine and chlorine shock treatments, dissolving it from the water before it can do its job. 

If you want to learn more about pool stabilizers, check out our article on the topic.

Standard, everyday chlorine, which you add to keep your pool water clean day-to-day, contains a stabilizer. These stabilizers are usually made from cyanuric acid, which creates a protective barrier around chlorine molecules. 

This barrier prevents chlorine from breaking down too fast and dissolving in the sunlight. However, it also makes chlorine less effective. Thus, adding stabilized chlorine with pool shock can cause your shock to stabilize and not “shock” the bacteria and algae out of your pool water. 

What Happens if You Get in Pool Water With Shock in It? 

Pool shock can cause skin irritation, eye pain, and other harm to the outside of your body. Chlorine can also hurt private areas if left on the skin’s surface and has been known to sometimes cause urinary tract infections. 

This isn’t to say that chlorine kills you if you accidentally step into the water when there’s shock in it. Rather, it means you’re likely to experience irritation and potential eye harm if you swim in the water. 

Chlorine shock isn’t likely to seriously harm you unless you swallow a lethal dose of chlorine in a swimming pool. Since there’s so much water in a pool, chlorine would have to be astronomically high to poison or cause lethal bodily harm. 

Pool shock is not harmless, but don’t think you’ll die because you step into the water. If you accidentally enter the pool while the chlorine levels are high, get out quickly, bathe, and wash your clothes right away. 

When Should You Use Pool Shock? 

Chlorine pool shock should be added in the evening or at sunset. You want to add the shock treatment when the sun’s no longer high in the sky and can damage the chlorine molecules. 

Adding chlorine shock in the evening or as the sun sets prevents the sun from damaging the chlorine. This will give the chlorine shock enough time to sterilize the bacteria and algae particles in the water. Chlorine shock oxidizes these particles and creates chloramines, a type of chlorine gas. 

You don’t have to add non-chlorine shock in the evening, however. Since there’s no chlorine in the shock, the sun’s UV rays won’t impact it. 


Adding pool shock is one of the best ways to sanitize and rebalance your swimming pool chemistry. If you struggle to eliminate algae bloom or bacterial growth in the water, it might be time to shock your pool water. 

Pool shocks come in chlorinated and non-chlorinated varieties. We suggest using the chlorine-based shock when the pool’s very dirty and unbalanced. However, non-chlorine shock is a suitable alternative for basic cleaning or if a family member is allergic to chlorine.

If you’re eager to learn more about pool maintenance, check out our blog. We have several articles on proper pool care and maintenance to help keep your water clean and sanitary.   


How Do You Test Free Chlorine Levels? 

The free chlorine in your swimming pool is the amount of available chlorine in the water to sanitize it. This chlorine differs from compound chlorine since compound chlorine is a combination of contaminated chlorine and free chlorine. 

Digital testers are the best way to test the free chlorine levels in your pool. However, you can also find water and test strip kits at the local pool store. 

What is Calcium Hypochlorite? 

Calcium hypochlorite is a common chemical compound used to purify water. While it contains chlorine, it’s not the same as pure pool chlorine. 

Is Chlorine the Same as Shock Treatment? 

No, chlorine is not the same as shock treatment. While chlorine shock treatment contains chlorine, it doesn’t have stabilizers. Stabilizers are useful in preventing chlorine decay but can slow down the oxidation process in shock treatments. 

Thus, shock contains chlorine, but it’s not the exact same compound as chlorine. 

Should You Use Granular Chlorine or Liquid Chlorine? 

Whether you use granular chlorine or liquid chlorine is ultimately up to you. Liquid chlorine mixes into the water quicker and typically contains more stabilizers. Granular chlorine takes longer to dissolve, but won’t impact your pool’s pH as much.