The Complete Guide to Shocking Your Swimming Pool

Shocking your swimming pool is a crucial part of pool care, and as a pool owner, you really need to know how to do this in order to keep the water clean and algae-free.

But before you throw your hard-earned money away on a professional, check out our guide here to see how easy it is to do it yourself.

It may take a little time out of your day, but once you get the hang of it, you’ll be a pro yourself in no time.

What is Pool Shock?

The process of shocking your pool is simply super-chlorinating it for a specified period of time in order to kill anything floating around that doesn’t belong.

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Certain algae, germs and debris can only be completely eradicated with the shocking process.

What the industry calls pool shock is simply the product you use to get the job done.

Why You Need to Shock Your Pool

Certain living organisms can still survive in your pool with its normal chlorine amounts. Others can become completely immune to it.

There are basically three reasons to shock your pool:

Sunshine breaks down your chlorine, causing it to lose up to 5 ppm per day.

Swimmers are constantly bringing in contaminants like makeup, sweat and bacteria that normal chlorine levels can’t always fight.

Rain showers can dilute your pool, leaving you with very low chlorine levels.

When to Shock Your Pool

Most people only decide to shock their swimming pools when they see an overgrowth of algae or the water starts getting cloudy, but by this time, cleaning your pool could take a lot more work.

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So if you stay on top of this chore by shocking your pool once a week, you may be able to avoid an algae overgrowth.

This kind of contamination often requires way more scrubbing, vacuuming and sometimes even draining than you will ever want to do.

BUT…in case you are like the rest of us and occasionally put things off, here are the times when you should shock your pool even if you don’t feel like it:

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    Before you first use your pool for the season. Your pool definitely needs a pre-boost of chlorine before everyone starts jumping in with all their germs. It’s especially important if you’ve had a cover on all winter. Who knows what might be lurking under there?
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    Before you cover it up for the winter. If you are about to close up shop, there could be algae spores or other matter in there just waiting to make a home in your crystal clear water. Get ahead of it by killing it before it grows..
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    After extreme weather conditions. Heavy wind or rain can carry in debris and algae spores that can get out of hand quickly if you don’t take charge immediately.
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    After heavy use. Did your kids recently have a pool party? All kinds of icky junk can be transported into the water by humans and pool toys. Get rid of that leftover sweat, makeup and who knows what else before it clouds up your water.
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    At the first sight of algae. Algae spores can bloom and spread quickly. Don’t let your pool get overtaken before you take action.

Types of Pool Shock

There are several different types of pool shock on the market and it’s important to know the difference before you decide which one is right for you.

Calcium Hypochlorite


Calcium hypochlorite is usually granular and also sometimes called cal-hypo shock.

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In The Swim Chlorine Pool Shock - 24 X 1 lb. bags
  • 24 x 1 pound bags
  • Powerful and effective chlorinated shock treatment

According to American Chemistry Council, it “destroys germs that are capable of causing numerous health problems for pool users--diarrhea, swimmer's ear (a nasty earache) and various respiratory, skin and wound infections.” 

This is the most popular shock purchased because it’s considered the strongest and it’s also the cheapest.

It dissolves quickly and should be used at night because it’s adversely affected by sunlight.

Lithium Hypochlorite


Lithium hypochlorite is usually used in pools with high calcium levels because it doesn’t contain calcium itself.

It also does not have to be pre-dissolved making it slightly more convenient than other shocks.

Sodium Di-Chlor


This is a granular shock that dissolves slowly, so it’s cleaning power lasts longer than cal-hypo.

It’s another highly popular pool shock because of its availability.

Potassium Peroxymonosulfate


This one is oxygen-based instead of chlorine-based, and it oxidizes the water and boost chlorine levels.

In The Swim Chlorine-Free Pool Swimming Pool Shock - 24 x 1 Pound Bags
  • Powerful oxidizing agent burns off dead chlorine cells and provides higher free chlorine levels
  • Chlorine-Free shock oxidizes and eliminates algae growth and harmful bacteria

People can actually swim very soon after this treatment is applied so it’s a popular shock to use in between super-chlorinating during heavy swim times.

How to Shock Your Pool in 5 Steps

Now that you know all the facts about what it is and why it’s important, it’s time to get down to business and get this job done.

Protect Yourself

Pool shock can harm your skin and bleach your clothing, so make sure you wear clothes you don’t mind ruining, gloves and protective eyewear.

Prepare the Chemicals

Once you’ve chosen your pool shock, you will need to read the manufacturer’s instructions and prepare it accordingly.

For example, granular shock will usually need to be dissolved in a five-gallon bucket of water before it’s poured into the pool.

But other shock, such as lithium hypochlorite can be poured straight in.

You'll also need to determine the proper amount of shock to use with your particular size of pool and prepare it accordingly.

Shock the Pool

Poor the shock and water solution into the pool according to the manufacturer’s instructions.

Some will recommend you disperse it evenly around the edges and others will tell you to pour it in close to the jets to circulate it.

Leave it Alone

Leave the shock in the water to do its work.

The manufacturer’s instructions are important here as well to make sure no one gets in the water too soon after treatment.

It’s usually recommended that you leave it overnight.

Check Your Pool Chemistry

After you’ve waited the recommended number of hours, you still need to test your pool’s chlorine levels before letting anyone swim.

Make sure the levels have returned to normal before you allow anyone in.

Frequently Asked Questions

Shocking the pool can be a little intimidating at first, so here’s some answers to the most frequently asked questions:

What's the Best Time of Day to Shock?

Most pool shocks are best used at night so that the sunlight doesn’t decrease its effectiveness.

It’s also best to shock at night so that it can be left alone for several hours, giving it time to work.

How Long Does it Take to Shock a Pool?

The actual process shouldn’t take more than an hour, but depending on the product used, it could be up to 8 hours before you can use it.

How Long After Shocking Is It Okay to Swim In?

When using a chlorinated shock such as di-chlor or cal-hypo, you will need to wait the recommended amount of time before swimming, usually overnight.

When using a non-chlorinated product, however, it’s usually safe to swim after about 15 minutes.

Additional Tips

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    After the pool shock is added, pool toys and accessories can also be thrown in for decontamination.
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    Never add pool shock directly to the skimmers.
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    Keep the pool uncovered until chlorine levels return to normal.
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    NEVER swim before checking to make sure the chlorine levels are at 3 ppm or less.
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    Use the entire amount of shock necessary for your pool’s size.
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    Don’t use shock on windy days. The product needs to stay in the pool, not in your face!
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    Shock your pool once a week to keep contaminates and algae from becoming a problem.
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    You can brush your pool after shocking to distribute chlorine more evenly.

Wrapping Up

Nobody likes a dirty pool.

Take it from me—if you shock your pool once a week, it will save you HOURS of cleaning time in the long-run. 

Killing algae spores and bacteria before they spread is the number one way to stay ahead of pesky pool maintenance tasks once and for all. So, don’t neglect it.

Shock your pool on Monday and enjoy it the rest of the week!

Pool Care Guy
 

Hi guys! My name is Mike, aka Pool Care Guy. I'm here to help you make sure your pool is clean, healthy, and pristine. Most of all, I'm here to guide you along so you spend more time swimming in your pool than you do cleaning it!

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