What is chlorine shock in a pool
Chlorine shock is an intensive disinfection treatment that consists of adding a high dose of chlorine in a short period of time. Its goal is to eliminate microorganisms, algae, bacteria, and organic residues that regular maintenance chlorine cannot neutralize.
This process also breaks down chloramines, compounds responsible for the strong “pool” smell and for eye and skin irritation. Applying a chlorine shock restores the water’s clarity and reestablishes its disinfecting capacity.
Why a shock treatment is necessary
Even with regular maintenance, pool water is constantly exposed to dirt, sunscreen residues, sweat, or even rain. Over time, these particles saturate the regular disinfectant and reduce its effectiveness.
Shock treatment is necessary to:
- Recover cloudy or greenish water.
- Restore free chlorine levels.
- Prevent the spread of algae and bacteria.
- Improve swimming safety and water quality.
When to perform a chlorine shock in the pool
There are key moments when chlorine shock is especially recommended:
- Start of the season: before the first swim, after filling or uncovering the pool.
- Heavy use: after parties, gatherings, or several days with many bathers.
- Altered water: when turbidity, bad odor, or a greenish color appears.
- After storms or heavy rain: as they alter pH and bring in debris.
- End of the season: before covering the pool for winter.
How to apply chlorine shock step by step
For the treatment to be effective, it is important to follow an ordered procedure:
- Measure and adjust pH: it should be between 7.2 and 7.6.
- Calculate the correct dose: depends on the product, usually 15 to 20 grams per m³ of water.
- Dilute the product: dissolve the chlorine in a bucket of water before adding it.
- Distribute in the pool basin: pour the mixture around the perimeter to spread it evenly.
- Keep filtration active: leave the system running for at least 6–8 hours.
- Wait before swimming: do not swim until free chlorine levels are between 1 and 3 ppm.
Tips to maximize treatment effectiveness
- Apply shock in the evening or at night to avoid chlorine degradation by sunlight.
- Brush walls and floor before treatment to loosen algae and adhered dirt.
- Check chlorine levels again the next day to ensure they are back to safe values.
- Repeat the process if water remains cloudy or algae are still present.
Common mistakes when applying chlorine shock
- Not adjusting pH before treatment.
- Pouring the product directly into the water without diluting it.
- Not waiting long enough before swimming.
- Relying on shock as the only maintenance method.
Alternatives and complements to chlorine shock
In addition to chlorine, there are other shock treatments that can be used depending on each pool’s needs:
- Active oxygen: suitable for sensitive skin and odor-free.
- Bromine: recommended for spas and hot water pools.
- Algaecides: complement shock to prevent algae growth.
Each product has its advantages and limitations, but chlorine shock remains the most widely used option thanks to its effectiveness and quick action.
