Shocking your pool is crucial for maintaining clear and healthy pool water. Whether you’re dealing with algae growth or preparing for a big pool party, understanding how to shock your pool is essential for keeping it safe and inviting. In this step-by-step guide, our pool repair and maintenance professionals will cover the types of pool shock, how to successfully shock your pool, and circumstances that may require additional TLC. Let’s get started!

What Is Pool Shock and Why Is It Important?

Chlorine is designed to combat bacteria, germs, and algae, ensuring the pool remains safe for swimming. However, as it does its job, chlorine interacts with substances like ammonia from swimmers, fertilizers, bird droppings, sunscreen, and other debris, forming chloramines. These chloramines not only produce a strong, unpleasant odor but can also lead to skin and eye irritation. Shocking the pool is essential to remove these inactive chloramines (also called combined chlorine) and restore your pool’s sanitizing power.

As a general rule, we recommend shocking your pool water as part of a weekly maintenance routine during the swimming season to keep it clean and balanced. Depending on your chlorine test results, you will have to choose between specific types of pool shock. For instance, if chlorine levels are below 2 ppm, a chlorine-based shock is ideal to restore proper sanitization. On the other hand, if chlorine levels are above 2 ppm, a non-chlorine shock may help kill bacteria without raising chlorine levels further.

Pool Shock Types

Selecting the appropriate type of pool shock for your swimming pool depends on your specific water chemistry needs. Here’s a breakdown of the main types of granular pool shock:

Calcium Hypochlorite (Cal-Hypo Shock)

Commonly referred to as cal-hypo, this shock is a potent chlorine-based treatment that effectively eliminates algae, bacteria, and other contaminants. With a high pH of 10.8, it’s ideal for pools with low to normal pH levels. However, cal-hypo contains calcium, making it less suitable for pools with high calcium hardness, as it can contribute to scaling. This shock is particularly useful after a pool party or when tackling stubborn algae blooms.

Dichloro-S-Triazinetrione (Dichlor Shock)

Known simply as dichlor, this shock is stabilized with cyanuric acid (CYA), helping to protect chlorine from being broken down by sunlight. However, frequent use of dichlor can raise CYA levels over time, which is why it’s not recommended for indoor pools or pools already using stabilized chlorine. This type of shock works well for saltwater pools and pools that don’t rely on stabilized chlorine as their primary sanitizer. It’s an excellent option for boosting chlorine without significantly impacting pH or clouding the water.

Potassium Monopersulfate (Non-Chlorine Shock)

Often referred to as chlorine-free shock, this treatment focuses on oxidizing organic contaminants and freeing up available chlorine. It’s a fast-dissolving and quick-acting shock that won’t directly kill algae or bacteria but works to improve water clarity and reduce chloramines. Non-chlorine mixes are ideal for routine maintenance when free chlorine levels are between 2.0-4.0 ppm. With this shock, you can usually resume swimming within 15 minutes, making it highly convenient.

How to Shock Your Pool

Step 1: Gather Your Supplies

Before you begin, make sure you have everything you need to safely and effectively shock your pool. Essential supplies include:

Step 2: Test the Pool Water

Test your pool water balance using a reliable water test kit or test strips to ensure all chemical levels are balanced. If the Free Available Chlorine (FAC) is between 2.0 – 4.0 ppm, opt for a non-chlorine shock that is capable of killing bacteria without increasing free chlorine. For levels below 2.0 ppm, use a chlorine-based shock to restore sanitizing power.

Step 3: Circulate the Water and Add Shock

Turn on your pool pump and filter system. Then, following the instructions on your shock product, slowly add shock around the inside edge of the pool and let the shock circulate without disturbing the water. (How much shock treatment to add is typically based on pool size).

For best results, shock your pool in the evening or at dusk, allowing the treatment to work overnight without direct sunlight, diminishing the chlorine’s effectiveness.

Step 4: Let the FAC Level Drop

If you’ve used a chlorine-based shock, allow the pump and filtration system to run continuously for 6–12 hours to distribute the shock evenly. Retest the water afterward to check if the Free Available Chlorine level has returned to a safe range. High free chlorine levels can make the pool unsafe for swimming, so patience is key.

Step 5: Dive into Clean, Safe Water

Once the FAC level falls between 2.0 – 4.0 ppm, your pool is ready for swimming! Enjoy the crystal-clear, sanitized water and the peace of mind that comes with proper pool care.

Other Reasons to Shock Your Pool

There are a few other reasons pool owners may need to treat their pools with shock chemicals. Here are a few times it may be wise to shock your pool:

Let Bennington Us Handle the Hard Work!

Knowing how to shock a pool is essential for any commercial pool owner, but keeping your pool clean can be a time-consuming and complicated task. Let Bennington Pool Services take the hassle out of pool maintenance with commercial pool management in King of Prussia tailored to your needs. Contact us today to keep your swimming pool crystal clear and ready for enjoyment all season long!