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  • Writer's picturePool Protection Technologies

6 Reasons Why Your Pool is Cloudy After Shocking

Cloudiness in pool water following a shock treatment is a relatively common occurrence, particularly when using a granular chlorine shock. Don't fret, as it's typically a temporary situation that can be resolved within a day. However, if the cloudiness persists beyond this timeframe and obstructs your view of the pool bottom, it may indicate an underlying issue. Let's explore the six most frequently observed reasons for cloudy water after a shock treatment

1. High pH Level:

One possible reason for your pool being all cloudy after shocking is because the pH level might be out of whack. pH and Total Alkalinity are like the dynamic duo of pool water chemistry, super important to keep things in check. When the pH is low, your pool water turns acidic, and when it's high, it becomes basic or alkaline. If the pH level is too high, it can lead to calcium buildup, scaling, reduced effectiveness of chlorine, and ultimately, cloudy water problems.

So, if you've shocked your pool and it's looking all cloudy, it's a sign that the pH and Total Alkalinity might be off balance. Some pool shocks, like Calcium Hypochlorite (cal-hypo), have a high pH level. If you use this type of shock in a pool that already has a high pH, it's a recipe for cloudy water troubles.

Here's a tip: before you go ahead and shock your pool with any chlorine shock (especially cal-hypo), it's a good idea to test the water chemistry first. Make sure the pH level is around 7.2–7.4, slightly lower than the ideal range of 7.4–7.6. You can use a pH Reducer to bring the pH down before adding the shock. This not only prevents cloudy water but also helps the shock work better. Just remember to balance the Total Alkalinity within the ideal range of 80–120 ppm before adjusting the pH levels.

By taking these steps, you'll be well on your way to enjoying a clear and inviting pool without any cloudy water woes.

2. Insufficient Filtration

Cloudy water after shocking your pool isn't always due to chemical mistakes. Sometimes, the culprit is your pool equipment. Poor water circulation or an inefficient filter can prevent the shock from properly incorporating into the water and hinder the removal of microscopic contaminants, resulting in cloudy water.

Imagine someone adding sugar to a glass of stagnant water. If they stir the water after adding the sugar, it dissolves smoothly. However, if they leave the water undisturbed, it becomes cloudy. The same principle applies to your pool if you don't circulate the water after adding chemicals.

To avoid cloudy water, make sure to run your pool pump for at least one full turnover daily (approximately 8 hours or more), especially when using multiple rounds of shock. Regularly clean out the pump strainer and skimmer baskets, and monitor the pressure gauge on your pool filter to determine when cleaning or backwashing is needed. If your filter media is old and worn out, replacing it will help maintain efficient filtration.

Inadequate filtration can hinder the removal of small particles and debris, leading to cloudiness. Ensure that your filtration system is in optimal working condition, and consider running it for an extended period after shocking to assist in the clarification process. By prioritizing proper water circulation and efficient filtration, you can prevent cloudy water issues and maintain a sparkling pool.

3. High Calcium Hardness Level

High Calcium Hardness levels can contribute to the cloudiness of your pool water following a shock treatment. Calcium Hardness measures the concentration of calcium in the water and is often associated with hard water sources. However, the choice of pool shock can also impact these levels.

One specific type of shock, calcium hypochlorite (cal-hypo), has a notable effect on Calcium Hardness. Adding just one pound of cal-hypo to 11,500 gallons of pool water can increase the calcium content by approximately 5 ppm. If your pool already has elevated Calcium Hardness levels beyond the recommended range of 200-400 ppm, it may be advisable to consider alternative shock treatments such as sodium dichlor (Di-Zap) or sodium hypochlorite (liquid chlorine) to increase chlorine levels without affecting the Calcium Hardness. Chlorine-free oxidizing shocks can also be used when Free Available Chlorine levels reach 2.0 ppm or higher.

To mitigate cloudiness caused by excessive calcium levels, it is crucial to regularly test the Calcium Hardness of your pool water, particularly before using cal-hypo shock. Lowering Calcium Hardness is a more complex process compared to adjusting pH or Total Alkalinity. It involves partially draining and refilling the pool incrementally to dilute the calcium content.

By closely monitoring and maintaining the Calcium Hardness within the recommended range, you can prevent cloudiness caused by high calcium levels. Carefully selecting appropriate shock treatments and taking the necessary steps to manage Calcium Hardness will help ensure the clarity and quality of your pool water.

4. Algae Growth

Algae growth is a common cause of cloudy pool water, even after shocking. When algae thrives in the pool, it can lead to a hazy or turbid appearance. While shocking the pool with chlorine can help eliminate algae, sometimes it may not completely eradicate the problem, especially if the algae has already taken hold.

After shocking, remnants of dead algae cells and organic compounds released by algae can linger in the water, contributing to cloudiness. These particles are often challenging to filter out, resulting in persistent cloudiness. To address this issue, it's important to continue running the filtration system for an extended period, allowing it to capture and remove suspended particles. Regular maintenance and cleaning of the filter are also essential for optimal filtration efficiency.

If the cloudiness persists despite these efforts, it may indicate a more significant algae problem or underlying pool issues. Seeking assistance from a pool professional is recommended in such cases to assess the situation and provide appropriate solutions for eliminating algae growth and restoring water clarity. By maintaining proper pool maintenance practices and effectively managing algae, you can minimize the occurrence of cloudy water even after shocking, ensuring a clean and inviting swimming experience.

5. Organic Matter

Cloudy water in your pool can often be traced back to the presence of organic contaminants, such as leaves, pollen, or body oils. These substances can enter the pool through various means and contribute to the cloudiness of the water. To tackle this issue, it is crucial to conduct a thorough inspection of the pool before applying a shock treatment. Ensure that the pool is free from debris, such as leaves or other visible contaminants, and clean them out accordingly.

By taking these proactive steps to remove organic contaminants, you can greatly optimize the effectiveness of the shock treatment. When the pool water is free from debris, the shock can target and neutralize the contaminants more efficiently, leading to improved water clarity. It is essential to maintain regular cleaning routines to minimize the accumulation of organic matter and promote a clean and clear pool environment. By staying vigilant and addressing organic contaminants before shocking the pool, you can enjoy crystal-clear water and a more enjoyable swimming experience.

6. High Cyanuric Acid Level

One possible reason for cloudy water after shocking your pool is an elevated concentration of Cyanuric Acid. Also referred to as stabilizer or conditioner, Cyanuric Acid plays a beneficial role in pool maintenance. It acts as a protective "sunscreen" for chlorine, shielding it from degradation caused by the sun's UV rays. However, an excessive amount of Cyanuric Acid can have adverse effects, leading to ineffective chlorine and cloudy water following a shock treatment.

It's worth noting that sodium dichlor shock contains stabilized chlorine, which includes Cyanuric Acid. Therefore, it is essential to test your pool water prior to shocking to assess the Cyanuric Acid level. If the level exceeds the recommended range of 30–50 ppm, it is advisable to avoid using dichlor shock. Instead, consider using unstabilized chlorine, such as cal-hypo, and/or chlorine-free shock when appropriate. Lowering the Cyanuric Acid level in your pool requires dilution through partial draining and refilling of the water, similar to addressing Calcium Hardness.

By monitoring and managing the Cyanuric Acid concentration in your pool water, you can optimize the effectiveness of shock treatments and prevent cloudiness. Regular testing and appropriate chlorine selection will help maintain balanced water chemistry, promoting clear and healthy swimming conditions.


In conclusion, pool shock is essential for maintaining a healthy and clear pool. If your pool appears cloudy after shocking, test the water chemistry, inspect your equipment, and use a high-quality, fast-dissolving pool shock. By following these steps, you can address any imbalances, uncover underlying issues, and ensure effective shock treatment for a clean and enjoyable swimming experience.

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