The pool experts / What kind of chlorine should you use in your pool? | THE COOL POOL by Fluidra

Chlorine is the most popular pool disinfectant because it is efficient and affordable. There is a wide range of chlorinated products on the market and the best way to choose the most suitable one for your pool is to ask an expert. Below, you will find a brief description of four chlorinated products: dichloride, trichloride, and calcium and sodium hypochlorite


More commonly known as fast-acting or shock treatment chlorine, this is what you should use when your pool requires drastic disinfection in little time. For instance, if your pool has not been treated for a long time, if there has been a severe storm or if you have had a party with a lot of people swimming in it.

This type of chlorine dissolves and acts quickly. In addition, it contains a stabiliser that slows down the evaporation of the product.


If dichloride is known as fast-acting chlorine, trichloride is given the name of slow-acting chlorine. This product is used for keeping the water in good condition. The active ingredient is dissolved and released more slowly than dichloride and gives off what is called free residual chlorine. This is very important for removing any harmful microorganisms that may get into the water once disinfected.

The amount of product you should use will always be above 1 ppm, but the exact volume will depend on the number of bathers, the temperature of the water and its exposure to the sun.


Hypochlorites are the cheapest chlorine-based disinfectants on the market and have been successfully used for many years.

Calcium hypochlorite is a white solid that can be purchased in powder form or in granules. This product is easy to store and use. It kills a huge variety of germs, although as it is slow-dissolving it can clog up pool components, cloud the water, reduce pH and increase alkalinity.

In contrast, sodium hypochlorite is yellowish in colour and dissolves immediately. Although it is an extremely efficient product, it is more corrosive and unstable than calcium hypochlorite, so greater precautions must be taken when it is handled. To prevent the water from becoming too alkaline and the loss of efficiency, an acid should be used.