How to shock a swimming pool

How to shock a swimming pool

Whats Shocking a Swimming Pool

Have you ever overheard someone talking about shocking their pool? While this term may initially baffle you, shocking the pool is an essential part of maintenance. In swimming pool language, it means raising chlorine levels to such a great extent that every living thing in the water is killed by cell disruption.

Some people liken it to a lightning bolt literally ripping through the water, destroying everything in its path. A shock treatment will oxidise the water and clear out any inert chlorine making it very safe to swim in.

Why should you shock a pool?


It’s natural that over a period of time your pool will get dirty from debris, dust and leaves which may blow or fall into the water.  Sweat, saliva and sunscreen can also contaminate the water making it unhealthy, discoloured and dirty. When all these have built up, it’s time to shock a pool.

How often should you shock?

If you’re checking your pool and maintaining it with the right chemicals, you may not need to shock it that often. Many people like to shock every two months, to keep a check that the water remains sanitary and healthy. 

It’s advisable to shock a pool when it’s first opened for the season, after heavy usage or when there’s been a lot of rain. Another reliable indicator that it’s time to shock is when the water looks cloudy, and you can notice a build-up of algae. 

A smell of strong chlorine may mean there’s a build-up of chloramines - broken chlorine molecules, which can cause skin irritation and swimmer’s eye which is blotchy red eyes. If you’re in doubt whether it needs shocking or not, undertake a bacteria test strip or chloramine test to clarify your water quality.

How do you shock it?

There are a few steps to take to make sure that you shock the pool effectively. Clean the pool of any leaves or debris as this may lessen your chlorine’s effectiveness. Likewise, high pH levels will eradicate some of the chlorine’s killing power, so lower the pH to around 7.0 before shocking.

Check the dosage of chemical required to shock the pool. This will depend on pool size and the type of shock you are using, and some may require dilution in a bucket. 

Try to distribute the shock evenly on the pool surface with the pool pump running. It’s best not to put it in the pool when it’s windy as it may have undesirable consequences. The next day vacuum up the dead algae and give the pool a good brush, and backwash your filter. 

What happens when you shock the pool?

Using a chlorine shock will mean you are raising chlorine levels very high to around 10 parts per million. You need to give the chlorine time to settle, so you can’t go in the swimming pool for ten hours or until it drops to 4 parts per million.

The best time to shock is at night when the sun and the UV rays will not have a chance to dissolve the chlorine levels quickly. Don’t forget that a clean swimming pool is a safe one. 

Barrier Reef Pools Perth can cover all your swimming pool needs from maintenance to installation. Our quality, fibreglass pools are made in Western Australia and have lifetime structural warranties. With three showrooms in Perth, and 70% of our business coming from recommendations, we can guarantee you won’t be disappointed with our pools. Come and speak to one of our experts today.

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