Expert Verified Updated: March 2026

How Much Chlorine to Shock a Green Pool? - Shock Calculator

Calculate exactly how much liquid chlorine you need to shock your green pool. Uses the SLAM method based on your CYA levels to kill algae fast.

What is the SLAM Method?

SLAM stands for **Shock, Level, And Maintain**. To clear a green pool, you must raise the Free Chlorine (FC) to a specific target level (based on your CYA) and **keep it there** until the algae is dead, the water is clear, and you pass an overnight loss test.

Formula: Your Shock Level should be approximately **40% of your CYA level**. For example, if your CYA is 40 ppm, your shock level is 16 ppm.

Actionable Steps

Step-by-Step Algae Removal

1. Lower your pH to 7.2 before starting.
2. Add the calculated dose of liquid chlorine.
3. Brush the pool thoroughly to break algae bio-films.
4. Run the pump 24/7 and clean the filter daily.

Pro Tip: Only use **Liquid Chlorine** for shocking. Tablets and powders (Dichlor/Trichlor) will raise your CYA even higher. Calculate your maintenance doses with our Bleach & Chlorine Tool.

Pro-Tip

Formula: Your Shock Level should be approximately **40% of your CYA level**. For example, if your CYA is 40 ppm, your shock level is 16 ppm.

Frequently Asked Questions

Can I shock with chlorine tablets?

It is not recommended. Tablets dissolve too slowly to effectively 'shock' a pool. Liquid chlorine or calcium hypochlorite powder are the preferred methods for rapid algae removal.

How do I know if the algae is dead?

Dead algae will turn grey or white and settle on the pool floor. You must vacuum this debris out of the pool and clean your filter to complete the process.

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