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You should shock your pool when the water becomes too contaminated for a normal dose of chlorine to solve. Ideally, your free chlorine level should be between 1-3 parts per million to keep the water clean and sanitary. As long as you have your pool balanced this amount of chlorine should do the trick!

However, sometimes your pool gets too out of control! In these instances, you should use a non-chlorine shock or chlorine shock to get your water chemistry back to normal. If you aren’t sure when to add pool shock or how to get your free chlorine level balanced we’re here to help.

We’ll teach you all you need to know to effectively shock your pool!

How Do You Know How Much Shock Your Pool Needs? 

The point of adding pool shock to your water is to eliminate contaminant buildup. These contaminants often include minerals like calcium scale, algae, bacteria, oils, and chloramines.

Whenever you add chlorine to your swimming pool, the chemical reacts with the water and particles. This reaction forms a compound called chloramines which create a strong chlorine smell. Many of us associate this smell with clean pool water, but it’s actually a bad sign.

Since this smell is produced when bacteria and particles are dissolved, it’s a sign that your pool water is dirty. Adding pool shock will deplete these excess chloramines and bacteria, bringing your pool chemicals back to a balanced level.

To determine how much shock a pool needs you need to start by testing your pool chemistry. First, figure out how much free chlorine and combined chlorine your pool water has and how much shock it needs to balance your pool chemicals.

As a rule of thumb, you’ll need to add 1 pound of shock for every 10,000 gallons of pool water. However, this can vary depending on how badly unbalanced your pool water is and the underlying cause.

If you have a lot of algae growth or severe contamination issues, you might want to increase this dosage. If the pool water is very bad, most shock manufacturers recommend adding triple the amount of recommended shock.

What is Breakpoint Chlorination? 

Breakpoint chlorination is the point at which your chlorine levels will remove chlorine byproducts. To understand how this works, you need to consider how chlorine kills pool contaminants.

When your chlorine kills bacteria and dissolves particles it oxidizes these elements and creates chloramines. Breakpoint chlorination is the amount of chlorine needed to dissolve chloramines in the pool water.

Determining how much pool shock to add to eliminate chloramines involves some basic math. First, you need to determine your pool volume. You can find out how many gallons your pool is by performing the following equation:

Length x depth x width x 7.5 (there are 7.5 gallons per cubic foot)

As a general pool maintenance tip, you’ll need one pound of shock per 10,000 gallons of water. So if you have a 30,000-gallon pool, you’ll need around 3 pounds of shock to reach breakpoint chlorination. Test your pool with a test kit to determine the levels of free chlorine vs combined chlorine. Continue adjusting the chlorine levels to decide whether you need to add more shock to your pool.

How Do You Know If You Have to Keep Shocking Your Pool?

The perfect level of combined chlorine levels is zero, but 0.2 parts per million is also an acceptable level. Your free chlorine levels should be between 1-3 parts per million.

However, while shocking your pool, your chlorine levels will be up around 30 parts per million. This level is ideal for keeping your pool’s water chemistry balanced and achieving chlorine breakpoint.

You need to monitor your chlorine levels closely as you work to adjust your pool’s water chemistry. Too much shock can lead to over-chlorination, which can only be fixed by draining some water and adding fresh water.

How Do You Prepare Your Pool For a Shock Treatment? 

Chlorine shock is usually added to a swimming pool to either kill bacteria or kill algae growth in the water. Before you shock a pool you’ll need to scrub the pool walls and floor with a pool brush. Scrubbing your pool works to loosen particles and algae growth that are clinging to your pool surface.

If you don’t get these particles freed from your pool surface they may be able to survive the shock in the pool. If you have teal green pool water, green water, or black or yellow spots on your pool surfaces, you need to scrub your walls a lot before you shock a pool.

Shocking your pool will kill bacteria and algae in the water, but if they’re hiding away on the walls they might survive the shock! If you want to learn more about how to kill yellow and black algae in your swimming pool, check out our articles on the subject.

Other than scrubbing and vacuuming your pool, you’ll want to balance your pool’s pH level. if your pool’s pH levels are unbalanced it can impact how the chlorine shock purifies the water. Get your pool pH to between 7.4-7.6 before shocking your pool to ensure the chemicals do their job well.


Pool shock gets your swimming pool water balanced and cleaned. It’s a super dose of sanitizers that work to break down large particles in the water and remove heavy bacteria and algae contamination.

Most pool shock comes in either non-chlorine shock or calcium hypochlorite chorine. Non-chlorine shock is better for hot tubs and spas since these usually use bromine rather than chlorine.

A swimming pool uses chlorine pool shock that contains calcium hypochlorite. Both of these varieties are powerful at balancing your pool water and keeping away unwanted organic debris and heavy particles.

If you’ve tried shocking your pool several times and still suffer from cloudy water, you might need to add a clarifier or flocculant! If you want to learn how to clean cloudy water check out our two articles on the subject!


How Do You Know if a Swimming Pool Needs Shock?

The tell-tale that it’s time to shock a pool is the presence of bacteria, algae, or cloudy water. Pool shock also helps balance your water to ensure the pH is balanced at the ideal neutral levels. if you’re struggling to keep your water chemistry balanced and cleaned it might be time to add pool shock!

Is Liquid Chlorine Shock Better than Granular Shock?

Liquid chlorine is the better option for shocking your pool if you need a powerful dose of sanitizer. Liquid chlorine pool shock acts faster since it doesn’t contain a stabilizer. While a stabilizer is great for regular chlorine since it prevents the chlorine levels from dropping due to UV rays, it can also slow down the efficacy of the pool chemical.

When Should You Add Pool Shock to Your Water?

Nighttime or sunset are the best times to add pool shock to your swimming pool. Since pool shock doesn’t usually contain cyanuric acid as a stabilizer, adding it at night will ensure it has a chance to do its job. Never shock your pool during the day since the UV rays will dissolve the chlorine levels before they get to sanitize the water.

Should You Run Your Pool Pump After Shocking Your Pool?

Keeping your pool pump running is an important part of effectively adding shock treatment to your pool. Let your pool pump run for between 6-8 hours after you shock your pool. This will not only ensure the chemical gets evenly dispersed, but will ensure the algae, bacteria, and other particles get pulled from your swimming pool!

Can You Over Shock a Pool?

Yes, you can over shock your pool. To prevent this from happening, check your water pH and chlorine levels regularly. This is the best way to ensure your free chlorine levels are balanced and doing their job properly.

If you’ve over shocked your pool, you’ll need to add fresh water to counteract all the chemicals in the water. Add the water, test the levels, and add chlorine until your free chlorine is back to proper levels.