Shocking Your Pool: Guide to Swimming Pool Shock Treatments

If you’re new to swimming pool care, you’ve probably heard of shocking a pool -- but you might not know exactly what it is, or when and why you should do it.

The good news is that shocking your swimming pool is relatively simple. In this article, we’ll review the basics of pool shock and answer some commonly asked questions about the not-so-shocking world of pool shock.

What is pool shock?

You might be surprised to learn that pool shock is really just an ultra-high dose of pool sanitizer. You can purchase shock at any pool supply store. There are shock options also available that breakdown contaminants without adding chlorine. Speak to your local pool professional for more information.

What does pool shock do?

Adding pool shock to your pool is kind of like power-washing your swimming pool water. By adding a higher-than-normal dose of pool sanitizer to your pool water, you’re effectively killing algae, bacteria, and other contaminants. Also this removes chloramines that cause the water to have that chlorine smell and may irritate the eyes.

Keep in mind, of course, that pool shock isn’t meant as a replacement for routine swimming pool maintenance: It’s just an extra-powerful addition that can help keep your pool clean and healthy.

For a complete maintenance guide on how and why to shock your pool, click here.

Which type of pool shock is right for you?

There are three basic types of shock treatments available for your pool. The type of shock treatment that you choose will depend on a few factors, including your budget, water chemistry and how quickly you want to swim after you shock your pool.

  • Calcium hypochlorite - or “cal hypo,” as the pros say, is a super-concentrated form of chlorine that’s sold in granular form. It’s super-effective at killing algae and harmful bacteria. Cal hypo is most effective when used at night. Always follow label directions when using this product and never mix with other chemicals.

  • Dichloroisocyanuric acid, also known as “dichlor,” is a formulation of chlorine and cyanuric acid. This product carries many advantages when shocking your pool. Consult with your pool professional to understand if your pool is right for this product.

    Always follow label directions when using this product and never mix with other chemicals.

  • Non chlorine shock. Sometimes shortened to “MPS,” this oxygen-based shock treatment is an excellent choice for odor removal and neutralizing ammonia and other contaminants. If you're battling algae issues, though, MPS might not be the best fit: It’s much less effective at algae removal than chlorine-based pool shock.

Which pool shock is best? If you’re not sure which option is the best one for you, talk to your pool professional and ask for a few recommendations.

Recommended Brands

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Regal Pool Care Products include sanitizers, shock and algaecides in addition to the 3-Step System. Regal's 3-Step Pool Care System is an easy-to-use pool maintenance chemical regiment including sanitizers, shock and algae prevention chemicals.


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Ease into this pool season with PoolStyle's full line of swimming pool chemicals including sanitizers, oxidizers, algaecides, balancers and more. PoolStyle provides homeowners and pool professionals alike with safe and effective chemical products.


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Achieve crystal-clear, balanced water all swim-season long with Pool Season's outstanding range of swimming pool chemicals. From algaecides and sanitizers to shock and sanitizers, Pool Season has the pool chemicals you need to maintain a safe pool.


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Make pool care easy with E-Z Clor's complete assortment of swimming pool chemicals. E-Z Clor offers sanitizers, balancers, supplements and other chemical products to help you maintain the beautiful, crystal-clear pool water you love.


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