Everything You Need to Know About the Ins and Outs of Pool Shock

Do you know about the ins and outs of pool shock? Some people think that you can leave it in your pool all year long. Is that true? Is it safe? What does it do? What are the pros and cons of using it? Read this article to find out.

Pool shock is essential when it comes to protecting your swimming pool. Without proper treatment of the water, your pool is at risk of danger.

You can also use pool shock in larger outdoor pools to reduce organic compounds and contaminants that can harm swimmers, but have you ever wanted to learn more about pool shock?

In this article, you’ll find out when to use pool shock, other types of pool shock you can use, how often you can use pool shock, and different types of chemicals used as pool shock, and more. 

The a-B-C’s of Pool Shock

Pool shock is chlorine in liquid form that breaks down organic matter and prevents odor or taste. Chlorine is also what makes water safe for people and your pets.

There are 3 main reasons you have to shock your pool, and these are called the A-B-C’s of pool shock.

‘A’ Is for Algae

A for Algae

Chlorine, in large quantities, is the most effective algaecide, whether the algal is green, yellow, pink, or black. Algaecide can be used to keep pool algae under control, but pool shock is used to kill algae and clean the pool of contaminants.

Ensure that the pH is in the 7.1-7.3 levels for the chlorine shock to be as effective as possible. Active algal blooms can be killed with concentrations ranging from 10 to 30 parts per million (ppm) depending on the intensity of the algae.

‘B’ Is for Bacteria & Bathers’ Germs

‘B’ Is for Bacteria & Bathers’ Germs

A variety of sources can introduce bacteria into the pool, but most of them are harmless. However, dangerous bacteria may also be present. You can use chlorine shock to eliminate germs from a pool after extensive pool use, severe storms, or winters months.

You can also use chlorine to disinfect your pool from bathers waste, including skin, hair, lotions, cosmetics, and soaps, as well as urine, feces, and fungus. 

‘C’ Is for Chloramines, Contaminants, Cloudy Water

C’ Is for Chloramines, Contaminants, Cloudy Water

Combined chlorine is what causes red-eye and the presence of a stinky chlorine smell.

When chloramine surpassed the levels of 0.5 ppm, you should add enough chlorine or non-shock chlorine to break apart combined chlorine. 

What Are the Other Times to Use Pool Shock?

Shock the Pool in Start-up and Close-Down

For some, it’s best to shock your pool in preparation for the long winter ahead, and the first days of the end of the winter.

Shock Your Pool After Heavy Rain

Shock Your Pool After Heavy Rain

Rain is pure water, but as it falls through the air, it attaches to airborne particles straight to your pool. Air pollution, dust, pollen, algae spores can change the chemical balance of your pool.

Shock Your Pool for Too Many Chloramines

Chloramines are useless and irritate the swimmer’s eyes. It also produces a strong smell of chlorine. You can easily test your pool of chloramines with DPD test kits. If chloramines exceed 0.3 ppm, it’s best to shock your pool.

How Often to Use Pool Shock?

You don’t want to wait until your pool produces an unpleasant odor or irritates your eyes before shocking it. We recommend shocking your pool every week, or at least every other week, to ensure proper water chemistry. The more often people use your pool, the more you should frequently reach for the swimming pool shock. 

Along with your weekly or semi-weekly pool maintenance, you may have to do an extra pool shock under these circumstances;

  • Large crowds in your pool (pool party)
  • Heavy rain and damaging winds
  • Major water level change
  • Bowel-related swimmers accident

What Are the Chemicals Used as Pool Shock?

There are several EPA-approved chemicals that you may use to shock your pool, especially if its regularly chlorinated with chlorine or bromine. However, the best ones depend on the pool type and issues you like to resolve, such as high cyanuric acid levels. 

Calcium Hypochlorite

Calcium hypochlorite is commonly known as “Pool Shock” because it will quickly remove all traces of organic matter such as algae, dirt, oils, etc. while leaving only calcium carbonate.

In addition, this product does not leave a residue when rinsed out of the pool. The Environmental Protection Agency has permitted this chemical for use in swimming pools.

Sodium Dichlor

Sodium Dichlor

Sodium dichlor is an inorganic compound approved by the EPA for use in pool shock to reduce total chlorine levels and sanitizer demand. This product works well with bromine and less with chlorine.

Potassium Monopersulfate

Potassium monopersulfate (also known as Sodium Bisulfate) is a powerful oxidizer. Potassium monopersulfate pool shock helps keep cyanuric acid levels low in pool water. It will also lessen the overall chlorine demand of your pool and boost the performance of chlorine-based sanitizers.

Advantages of Non-Chlorine Shock

  • Non-chlorine-based products won’t cause any eye irritation problems.
  • Great for removing odors from your pool.
  • Non-chlorine-based products help maintain healthy bacteria levels in your pool.
  • Safe for children and pets.
  • Easy to apply.
  • Effective against most common contaminants found in pool water, including viruses, mold, mildew, fungus, algae, and even oil spills!
  • Inexpensive compared to traditional methods.
  • Provide immediate results.
  • Environmentally friendly.
  • Available in different forms

Disadvantages of Non-Chlorine Shock

  • Some users find it difficult to mix properly
  • Too little can result in poor cleaning effectiveness.
  • Not as effective as algaecides
  • Not as efficient as bacteria treatment

Chlorine Shock Pros

  • Can be applied at any time during the year
  • Don’t need special equipment to administer chlorine shock
  • Fast action
  • No residuals after application
  • Cost-efficient
  • Removes harmful microorganisms
  • Reduces the risk of disease transmission

Chlorine Shock Cons

  • Requires regular monitoring of pH/alkalinity
  • May require additional testing if using non-EPA approved chemicals
  • Must be mixed correctly before being added to the pool
  • Doesn’t work effectively on some contaminants

What’s the Right Pool Shock to Use?

A golden thumb of rule to follow is to dissolve one pound of either calcium hypochlorite or sodium dichlor for every 10,000 gallons of pool water in the pool. If you’re using sodium hypochlorite, often known as liquid chlorine, the ratio is 10 ounces per 10,000 gallons of pool water.

A lot of pool owners may lose their pool care guide, so if you’re pretty unsure how many gallons of water you have in your pool, here’s an easy formula you can use.

Length of your pool in ft x width in ft x depth in ft x 7.5 = volume in gallons

You may also use the Pool Volume Calculator built into the Pool Calculator App, which is accessible on the web or as a Native App for iOS and Android devices.

What Happens When You Put a Lot of Shock in the Pool?

Adding a large amount of shock to your pool merely for its sake will not expedite the cleaning process in any way. If it’s your first time shocking your pool, and you see the pool’s water starts to turn cloud, don’t panic and start dumping more shock in your pool.

Cloudiness is expected when you shock your pool. But to clear out the cloudy water, you have to turn your filter and pump on continuously for about 4-6 hours.

Cloudy Pool Water

It may take 4-6 hours for the cloudiness to disappear, but you should not test your pool’s chlorine levels on the same day that it has been shocked. Because of the high chlorine levels, the test strip will get bleached, giving you a misleading reading. 

Getting a misleading reading may lead you to believe that your pool lacks sufficient shock when in fact, the opposite is true. To avoid accidentally adding too much chlorine, it’s advisable to wait a few days before testing the water again. If you accidentally put too much shock in your pool, the best thing you can do is to wait it out. 

Pro tip: the more sunshine your pool water receives, the quicker the shock disperses.


You may not be concerned about excessively shocking your pool right now, but each component of the shock treatment is crucial. To achieve good results and return to swimming, it is vital that you get the process correctly. Learning the ins and outs of how to shock a pool can assist you in maintaining your pool more effectively in the future.

Browse our collection of articles on our website. You can find a few tips below for cleaning and maintaining your pool. Enjoy a fun time in a clean, safe pool with your family!

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About the author

Brian Anderson

The rather dry pool world out there is in need of some passion to make it shine. With the help of my son Ruben and his wife Maria our mission is to help you create the favorite spot of your house - your pool.

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