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What is Pool Shock Treatment? Van Nuys CA Guide to Effective Water Sanitation

Marty • November 16, 2024

Pool shock treatment is a vital maintenance process...

...for keeping your swimming pool clean and safe in Van Nuys, CA. Pool shock is a concentrated dose of chlorine or other oxidizing chemicals that eliminates contaminants, kills bacteria, and restores water clarity. This powerful treatment works by rapidly raising the chlorine levels in your pool, effectively destroying harmful microorganisms and organic matter.

You'll typically need to shock your pool after heavy use, rainstorms, or when you notice signs of algae growth. Before applying shock treatment, it's crucial to test your pool water's pH levels and adjust them to between 7.2 and 7.8 for optimal results. This ensures the shock treatment can work efficiently to sanitize your pool water.

When using pool shock, you'll dilute the product according to the manufacturer's instructions and evenly distribute it around your pool. It's best to shock your pool in the evening or at night, allowing the chemicals to work undisturbed. After treatment, you should wait until chlorine levels return to normal before swimming again, typically 24 hours or less.

Understanding Pool Shock Treatment

Pool shock treatment is a normal maintenance process that keeps your swimming pool clean and safe. It involves adding a high concentration of chemicals to your pool water to eliminate contaminants, bacteria, and algae. By regularly shocking your pool, especially during the summer months, you help maintain water clarity and reduce the growth of microorganisms.

The Importance of Regular Shocking in Pool Maintenance

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  • Regular shock treatments are essential for controlling algae and bacteria in your pool. These microorganisms can multiply rapidly, especially in warm conditions or after heavy use.
  • Shocking your pool weekly helps eliminate existing algae and prevents new growth. It oxidizes organic matter that algae feed on, making the environment less hospitable.
  • For bacteria control, shocking destroys harmful microorganisms that can cause illness. This includes E. coli and other pathogens that may be introduced by swimmers.


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UV rays can deplete chlorine levels, making your pool more susceptible to algae and bacteria. Shock treatments replenish the sanitizer, maintaining protection between regular chlorine additions.


Consider using an algaecide in conjunction with shocking for enhanced protection against stubborn algae strains.

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Shock treatments play an important role in balancing your pool's chlorine levels. They convert combined chlorine (chloramines) back into free chlorine, which is the active form that sanitizes your pool.


Free chlorine should be maintained between 1-3 ppm for effective sanitation. Regular shocking helps achieve this by breaking down chloramines and boosting free chlorine levels.

Types of Pool Shock Products

Pool shock products come in different formulations designed to effectively sanitize and clean pool water. To get a better understanding we will ‘dive’ right into each of the types:

Calcium Hypochlorite for Effective Treatment

Calcium hypochlorite, often called cal-hypo, is a powerful and fast-acting pool shock product. You'll find it in granular form, making it easy to apply. This type of shock is highly effective against tough algae and bacteria.


Cal-hypo typically contains 65-75% available chlorine, providing a strong sanitizing punch. It dissolves quickly in water, allowing for rapid treatment of pool issues.


When using cal-hypo, apply it at night to prevent sun degradation. This product may slightly increase your pool's pH and calcium hardness levels.

Sodium Dichlor for Stabilized Sanitizing

Sodium dichlor, or simply dichlor, is a stabilized chlorine shock product. It contains cyanuric acid, which helps protect the chlorine from UV rays.


Dichlor usually comes in granular form and dissolves easily in water. It's gentler than cal-hypo, with about 55-62% available chlorine.


You can add dichlor directly to your pool water without pre-dissolving. It won't affect your pool's pH significantly, making it a convenient option.


This product is ideal for regular maintenance and works well in outdoor pools exposed to sunlight. Dichlor helps maintain a consistent chlorine level in your pool.


Non-Chlorine Shock (Potassium Peroxymonosulfate)

For chlorine-free pools or pools needing an extra cleaning boost, non-chlorine shock oxidizes contaminants without adding chlorine. This is a great choice for routine maintenance or when wanting to avoid raising chlorine levels.

Best Practices for Shocking Your Pool

Properly shocking your pool is a very effective way to maintain clean, safe water. Accurate dosage and careful application to ensure the treatment works correctly while protecting swimmers and equipment.

Steps to Shock Your Pool

  • Determining the Appropriate Pool Size and Dosage Calculate your pool's volume before shocking. Measure length, width, and average depth in feet. Multiply these numbers together, then multiply by 7.5 for gallons. Round up to the nearest thousand.
  • Check the shock product label for dosage instructions. Most require 1 pound per 10,000 gallons of water. Adjust based on your pool's specific needs and current chlorine levels.
  • Test your water before shocking: Aim for a pH between 7.2 and 7.6. If needed, adjust pH first for optimal shock effectiveness.
  • Apply Shock Treatment Safely: Shock your pool in the evening or at night. This allows the chemicals to work without sun degradation. Run the pump for at least 6 hours after shocking. Add shock directly to the water, not through skimmers.


  • Pre-dissolve granular shock in a bucket of water before adding it to the pool. Pour the solution around the pool's edge while walking.
  • Safety Precautions: Wear protective gear, goggles, gloves, and clothing that covers your skin. Brush the pool walls and floor after shocking to distribute the chemicals evenly. Wait at least 12 hours before swimming. Test the water again before use to make sure chlorine levels are back within safe limits.

Practical Tips to Make Pool Shock Treatment Successful

  • Check for Signs of Contamination: Cloudy water, a strong chlorine smell, or slimy pool walls can be a marker of the need for shock treatment.
  • The Use of an Algaecide in Stubborn Cases: For extra algae control, use shock treatments in tandem with an algaecide.
  • Environmental and Cost Considerations: Consider environmental factors (like local water and air quality) when choosing a shock product. Chlorine-free options can reduce the impact of chemical runoff. Additionally, knowing the relative costs of different shock types helps you budget for consistent maintenance.

FAQ's

  • How to shock a pool that is green?

    To shock a green pool, first test and adjust the pH to 7.2-7.8. Remove debris with a skimmer or vacuum. Calculate the pool volume and add 2-4 times the normal shock dose. Run the pump continuously for 24-48 hours. Brush the walls and floor daily until the water clears.

  • What does pool shock do to pH levels?

    Pool shock can temporarily lower pH levels. The oxidation process consumes alkalinity, which acts as a pH buffer. After shocking, test the water and add pH increaser if needed to bring levels back to 7.2-7.8. Maintaining proper pH helps the shock work effectively.

  • How long does it take to shock a pool effectively?

    Shocking a pool typically takes 24-48 hours to be fully effective. During this time, run the pump continuously to circulate the shock treatment. Avoid swimming until chlorine levels return to 1-3 ppm. Very cloudy or algae-filled pools may require longer treatment times.

  • How often should you shock your pool?

    You should shock your pool weekly during peak swimming season. Shock more frequently if the pool gets heavy use, after rainstorms, or if you notice algae growth. At minimum, shock monthly to maintain water quality and prevent contamination buildup.

  • What's the difference between pool shock and regular chlorine?

    Pool shock contains a higher concentration of chlorine than regular chlorine. Shock is typically 65-75% available chlorine, while regular chlorine is around 10-12%. Shock provides a quick boost to sanitize the water, while regular chlorine maintains daily chlorine levels.

  • What is pool shock treatment and how does it work?

    Pool shock treatment is a high dose of chlorine or other oxidizer added to pool water. It works by rapidly raising the chlorine level to kill bacteria, algae, and other contaminants. Shock breaks down chloramines, which cause eye and skin irritation. This process restores the pool's sanitizing ability.

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