Pool Shock Guide

Chlorine is known to kill harmful bacteria and prevent the growth of algae in swimming pools. However, it can also cause diseases if it gets mixed with other harmful elements in the water.

Why Shock Your Pool?

Shocking your pool regularly is important to prevent it from getting too chlorine-heavy. Chlorine levels can vary depending on the volume of contaminants in the water and the bather load.

Shock therapy lowers the chlorine level in the pool to break down the Chloramines. This method effectively cleans the water and prevents it from getting contaminated.

When testing for chlorine, the results can be determined by dividing the available chlorine by the total available chlorine. This method is usually used for determining the Free and Total Chlorine levels.


When to Shock Your Pool?

- Although applying shock to your pool is a regular part of your maintenance routine, some examples are more important than others.

- Rain & Thunderstorms: Storms can also contaminate your pool. They can also cause staining, which can lead to pool damage.

- Opening & Closing: After balancing the chemicals in your pool, shock it to kill the bacteria and improve the water quality. This will also help prevent staining.

- Algae Outbreaks: When algae appears in your pool, super-chlorination with powerful types of shock can often eliminate the problem.

- Heavy Pool Usage: Heavy pool usage can cause various issues when it comes to keeping the water safe. It is highly recommended that swimmers avoid using the pool during busy times.


Which Shock Should I use?

There are three types of shock:

- Cal Hypo (Calcium Hypochlorite)

- Dichlor (Dichloro-S-Triazinetrione)

- Chlorine-Free

Cal Hypo is a powerful shock that kills algae and contaminants. It's ideal for pools with a low pH level. Leslie's Power Powder Plus 73 is a great shock for removing chlorine and other harmful contaminants from the pool.

Power Powder Plus 73 is a powerful solution shock that can kill tough organic and inorganic contaminants. It can also be used weekly to clean up pool and spa.

A dichlor pool shock will not raise the pH level and will not cloud the water. A maintenance shock like Leslie's Chlor Brite will keep the chlorine levels at a safe level.

Chlorine-free pool shock is commonly used for quickly oxidizing contaminants, while also improving water clarity. It’s not harmful to algae or germs.

Aerated and cloudy water can be removed with this product. It helps keep your total chlorine and FAC levels the same.

Cal Hypo is a powerful shock that kills algae and contaminants. It is ideal for pools with a low pH level. Leslie's Power Powder Plus 73 is the strongest shock that provides 73% Calcium Hypochlorite and 70% Chlorine.

Power Powder Plus 73 is a fast acting and effective solution shock that can remove tough organic contaminants from water and its surroundings. It's also great for treating algae blooms.

A Dichlor pool shock is a quick-dissolving solution that will not raise the pH level. When chlorine levels are less than 2.0 ppm, use a maintenance shock such as Leslie's Chlor Brite. It will burn off quickly from UV rays and support the sanitizing efforts of both salt and tab pools.

Chlorine-free pool shock is great for quickly removing contaminants, but it won't kill algae and germs. Instead, it will improve water clarity and contribute to the development of enzymes. Leslie's Fresh 'N Clear is a non-chlorine shock that will remove ammonia and other organics from the water.

How to Shock a Pool

Step 1. Test the Water

Use a water test kit or test strips to ensure that the pH level is in the proper range.


Step 2. Circulate the Water, Pour the Shock

Use the shock product around the perimeter of your pool. The product should not be used inside the pool.


Step 3. Wait for FAC Level to Drop

For about 6-8 hours, run the pump and test the water. If the water is safe to swim, then leave it.


Step 4. Enjoy Clean, Safe Water


If the FAC level drops below 4 ppm, then wait until the shock level drops below that threshold. It is important to note that a Cal Hypo based shock can cause a small amount of calcium to cloud the water for a few hours.

The weekly shock helps free up Chlorine, which can be expensive to maintain. It can also help clear out algae, reduce chlorine levels, and provide a quick and easy way to reduce bather load.


If you have any other questions about pool and spa products please do let us know - we are here to help!

Leave a comment