Chlorine in swimming pools, everything you need to know

Chlorine is the essential chemicals when it comes to pool water treatment. Today we are going to learn about the different types of chlorine and how to use them in a proper way.

The benefits of chlorine

This product disinfects your pool by killing all the bacteria that can be found in the water. It is an effective treatment and one of the cheapest on the market.


Chlorine also acts as an oxidant. It is recommended to use it in outdoor pools or where the water receives sunlight, in this way the chlorine remains in the water for a longer time through its chemical stabilizers.

Types of chlorine

What most people do not know is that there are different types of chlorine and each of them has a specific function.

Shock chlorine

This chlorine is used especially when we open the pool after a period without using it. It acts quickly and reactivates the pool water getting ready for bathing again.


Then, you have to let it act in the water and after about 2 hours, that’s when we must adjust the pH between 7.2 and 7.6. To do this, we will measure it and then adjust it with a pH reducer or booster, depending on what our pool requires.


In a second phase, we can use shock chlorine to eliminate bacteria. The correct thing to do is to use this chlorine as an initial treatment adding 15g of chlorine for every m3 of water.


It must be done with the filtration running and after about 2 hours, re-analyze the pH and the chlorine level. This operation can be repeated several times until crystal clear water is obtained.

Slow chlorine

When we have already carried out the initial process with the shock chlorine, a daily maintenance of the pool is necessary. For this we will use slow chlorine, but be careful, we must make sure that the pH is adjusted before, otherwise the disinfection will not be effective.


It is advisable to use a floating dispenser for the use of chemical treatments.


We will place one unit of chlorine for every 25m3 of pool and let it act for all the water; for that we will switch on the filtration equipment. We must bear in mind that we can acquire chlorine in different formats: pills, tablets, granules, liquid …


Chlorine is a very effective disinfectant product, which means that we must take care when using it in some circumstances.


Prolonging the contact of trichlor compacts is not recommended, as it can bleach some surfaces such as vinyl, painted pools or polyester.


Furthermore, chlorine can damage very sensitive skin or redden the eyes if too much is used. Despite being the disinfectant par excellence due to its effectiveness and competitive price, it is not suitable for all skin types. For this reason, there are alternatives such as bromine, whose treatment is more specific.



If you still have any questions about chlorine, contact us!


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