How to Shock Your Pool

Swimming pools often add significant value to a home. That said, you’ll need to keep your pool clean and sparkling if you want your family and friends to enjoy it safely. Keeping a pristine pool requires an appreciable amount of maintenance. One specific technique you’ll need to be aware of is called pool shock.

File:Swimming-pool-chemicals-1.jpg“File:Swimming-pool-chemicals-1.jpg” by Scott Lewis is licensed under CC BY 2.0

What do you mean by “shocking a pool?”

Pools are nothing more than a giant quantity of water. Such spaces can easily turn into breeding grounds for potential illness-inducing materials like bacteria and other pathogens and allergens including dirt and dust, and plant forms like algae.

You “shock” a pool by administering powerful chemicals that are designed to eliminate any of these annoying, and sometimes hazardous, materials.

How to shock your pool

Shocking your pool includes several key steps. The first step is testing the pool’s water. This action is taken to ensure the pool’s pH balance falls within an acceptable range.

Once testing is complete, the water must be circulated. This task can be accomplished by switching on the pool’s filter pump.

After giving the pump a fair amount of time to circulate the water, the shock chemicals are added. Pool professionals suggest this activity be performed during the evening, which then gives the pump the opportunity to circulate the chemicals overnight.

The following day, you must carefully monitor the free chlorine level. This reading must fall between two and four parts per million, or PPM, before the pool is safe to use.

Types of pool shock

Currently, there are three major types of pool shock available to pool owners – Dichlor, Cal-Hypo, and Chlorine-Free. We’ll explain each.


This product, which in scientific terms is called dichloro-s-triazinetrione, is often employed because it neither clouds the water nor increases the pH level.


This product, short for calcium hypochlorite, is a powerful substance particularly known for its ability to eliminate algae.


Chlorine-free shock is considered optimal for improving a pool’s aesthetics. The product is lauded for its capacity to improve water clarity and maintain chlorine levels. That said, the product is not effective in eliminating pathogens and algae.

It’s important to know that every pool is different and pool shock is not one-size-fits-all products. Therefore, homeowners are encouraged to consult with a pool maintenance company that can do a consultation and determine the most appropriate product to use.

When should I shock my pool?

Shocking should be performed on a relatively regular basis. However, certain occasions warrant more frequent use such as:

After heavy pool usage

When large numbers of people use the pool in a short period of time it’s a good idea to use shock. An excessive number of people in the pool could result in a quicker and more serious contamination problem.

It’s always a good idea for a pool to be shocked following parties or any other occasion where you significantly exceed your pool’s normal capacity.

Following inclement weather

Shocking is also recommended following moderate to severe weather events like rain, wind, and thunderstorms. Rainwater can be contaminated with a wide array of pathogens, chemicals, and environmental debris. High winds can also blow potentially harmful materials like dirt and dust into the pool’s water.

When algae outbreaks occur

Algae growth must be eliminated as soon as possible. Fortunately, most shock treatments will quickly take care of algae issues.

At the beginning of each pool season

When you shock your pool at the beginning of the pool season, you’ll eliminate microbes, balance chemicals, and start the season with crystal clear water.

Benefits of pool shock

Pool shocking often produces several crucial benefits including:

Increased safety

Numerous contaminants enter pool water, such as microbes like viruses and bacteria, allergens, bird droppings, food and beverage particles, and even fertilizer. Any of these products could cause illness if they’re allowed to accumulate.

Shock products often neutralize these chemicals and prevent pool users from getting sick.


Over time, the chlorine used in pools combines with microbes and particles from contaminants to form byproducts called chloramines. Chloramines are notorious for giving off the heavy, offensive chlorine odor sometimes encountered when one steps poolside.

Shock often contains powerful chemicals like chlorine. These substances are not only strong germ killers but provide an additional sense of cleanliness. A cleaner pool offers a more inviting look to your pool’s water.

How often should I shock my pool?

Pool pros recommend shocking as necessary. The more often the pool is used, the more often the pool should be shocked. In general, a weekly schedule that alternates the application of chlorine and non-chlorine shock products will usually keep your pool’s water in good shape.

Sticking to this plan could prove beneficial on two fronts. First, potentially harmful contaminants are safely eliminated and gradually oxidized out of the water. Second, this strategy helps homeowners reduce chlorine use, which leads to lower long term pool expenses.

If you’re at the stage where you’re just researching your first pool, you’ll also want to think about pool equipment and accessories. Global Pool Products is your source for American made pool slides, ladders, railings, games and swim-up bars to turn your pool into the ultimate backyard oasis.

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