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Chlorine is the most commonly used chemical for keeping swimming pool water clean, safe and free from bacteria. Despite its effectiveness, it is important to know how to use it correctly to avoid problems with your skin, eyes and the structure of the pool itself.

In this article, we explain everything you need to know about using chlorine in swimming pools: advantages, types of chlorine, correct dosages and environmentally friendly alternatives.

1. Why is chlorine used in swimming pools?

Chlorine has a powerful disinfectant and oxidising action, capable of eliminating:

• Bacteria, viruses and fungi
• Algae and invisible microorganisms
• Organic impurities (such as sweat, saliva, sunscreen)

Thanks to its effectiveness, chlorine guarantees crystal clear and hygienically safe water, even in high temperatures or when there are many bathers.

2. The different forms of chlorine for swimming pools

Granular chlorine

• Rapid disinfectant effect
• Ideal for shock treatments or for starting up the pool at the beginning of the season

Chlorine tablets

• Slow and steady release
• To be inserted into the skimmer or floating dispenser
• Excellent for routine maintenance

Liquid chlorine

• Easy to dose in large plants
• Requires attention and automatic dosing systems to avoid errors

3. How much chlorine should be used in swimming pools?

The ideal dosage varies depending on the type of pool and frequency of use. In general:

• Recommended free chlorine: 1–1.5 mg/litre
• Shock chlorine: 10–15 mg/litre (start of season or emergencies)

Note: Excessive dosages may cause irritation and damage. Always use a tester to check levels.

4. When to perform shock chlorination treatment

• After storms or heavy rain
• In case of cloudy or green water
• At the season opening
• After intensive use (parties, many bathers)

5. Chlorine and pH: a fundamental balance

Chlorine only works properly if the pH is between 7.2 and 7.6.
If the pH is outside this range, chlorine loses its effectiveness.
Check and adjust the pH with specific products (pH+ or pH−) at least once a week.

6. Alternatives to traditional chlorine

• Salt-based chlorine (saline electrolysis)
• Active oxygen
• UV or ozone treatments

These are more environmentally friendly and gentle options, but in some cases they still require a small amount of chlorine for total safety.

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In summary

Chlorine is a valuable ally in keeping your pool hygienic and safe. Use it responsibly, monitor levels and also consider alternative solutions if you are looking for a more natural experience.