The Importance of Shocking Pool – When to Shock Your Pool

When To Shock Your Pool

Pool shocking is a recommended regular maintenance practice for any pool owner. It is, therefore, important to know when to shock your pool.

To ensure that sanitary conditions are maintained in your pool, this article explains what pool shock is and why it is important to apply it. Further, it discusses the conditions under which you should carry out the pool shocking process.

What is Pool Shock?

Pool shock is a powder/granular form of chlorine that acts as an oxidizer. It is essentially added to the pool weekly or whenever necessary, to get rid of germs and algae spores. For regular pool shocking, use 1lb. of shock per 10,000 gallons of pool water.

Why Do You Need to Shock Your Pool?

Pool shocking plays a role in maintaining or raising the level of free chlorine in your pool to at least 3 ppm (parts per million). This free chlorine is important to get rid of germs that may be deposited by swimmers, pool accessories, or even pets.

In addition, it eliminates algae spores that may have been introduced in your pool before they grow, spread, and become a menace in your pool.

Pool shocking is, therefore, a necessary sanitation practice that must be observed to ensure the comfort of swimmers. Always read the package label and take necessary precautions before applying pool shock.

When to Shock Your Pool

When to Shock your Pool


Free Chlorine Levels Drop Below 3 ppm

Free available chlorine is the active chlorine that actively kills germs in your pool. Centre for Disease Control recommends using a DPD test to check the level of free chlorine in your pool.

They also recommend a concentration of at least 1ppm. However, you should shock your pool whenever the free chlorine levels drop below 3ppm.

This will ensure your pool is sanitary and it also gets rid of algae spores that may be infesting your pool. Use a chlorine stabilizer like cyanuric acid to ensure the shock is effective for longer.

Before You First Use for the Season

This is especially important because free chlorine levels drop gradually even when the pool is not in use.

Shocking your pool before you first use it for the season will kill the germs that may have accumulated while it was not in use, and makes your pool safer for swimmers.

Before You Cover it up for the Winter

You should do this as a preventative measure. Shocking the pool will get rid of germs and algae spores that are likely to grow and spread in your pool while it is covered.

After Extreme Weather Conditions

When there are strong winds, it may deposit dirt and possibly algae into your pool. Heavy rain does the same and besides, it dilutes the pool water, lowering the chlorine concentration.

Shocking the pool will raise the chlorine concentration back to optimal levels and get rid of any debris and spores that may have been deposited during the extreme weather phenomenon.

After Heavy Use or Party

When the pool has been used heavily during a party, there is a possibility of high germ deposition in it through sweat and sometimes, urination, or drink spills. The pool accessories like toys and floats may also be laden with germs.

Shock your pool immediately after the heavy use and run the pump for at least 8 hours before the next use.

The Smell of Chlorine or Irritated Eyes

The smell of chlorine is the odor of combined chlorine (chloramines). This is chlorine that is already used up and the smell indicates lower levels of free (active) chlorine. Shocking your pool will replenish free chlorine levels.

When your eyes get irritated during a swim, it is an indication of alkalinity where the pool pH level is above 7.8 in which case you should add an acid. It also happens when the pH is below 7.0 which is an indication that your pool is acidic in which case you should add an alkaline.

In addition to balancing your pool levels to maintain it between pH 7.2 and 7.8, you should shock your pool.


In conclusion, regular pool shocking should be observed on a weekly routine. It is an important practice that maintains free chlorine levels in your pool at an optimum level allowing it to kill germs.

You should therefore shock your pool when the free chlorine levels drop below 3ppm, after heavy pool use, after extreme weather conditions, and before the first use of the season.

Additionally, you should also apply shock before covering your pool for winter and if you experience eye irritation after a swim or when your pool smells of chlorine.