Pool Chlorine Shock Dose Calculator for Australia

Planning on shocking your swimming pool but not sure how much chlorine you need to dose to do it properly? Use the calculator below to find out how to superchlorinate your pool with liquid or solid chlorine!

Note: Just want to add routine chlorine rather than shock your pool? Check out this chlorine calculator.

Why Shock Your Pool?

Shocking can be done periodically to sanitise the pool and maintain an adequate Free Chlorine (FC) level (usually if free chlorine is stubbornly low for a while), though it is more often done when an issue occurs in the pool, such as an algae outbreak.

Shocking is done to superchlorinate the pool water, killing all living organisms and rendering the pool safe for humans once again.

Contrary to what some pool owners think, salt water pools can be shocked.

How Much Shock Do I Need To Dose?

The generally accepted measure for superchlorinating your pool is to add 10 times the current Combined Chlorine (CC) level as available chlorine. So if you have a Combined Chlorine of 2 ppm, you should add 20 ppm worth of available chlorine.

Adding this amount of chlorine will ensure that you achieve breakpoint chlorination and are left with a residual Free Chlorine (FC).

To determine your current Combined Chlorine level, use a pool test kit or strips to determine your Free Chlorine (TC) and Total Chlorine (TC). Combined Chlorine is simply the difference between the two, so CC = TC - FC.

What Is Available Chlorine?

Available chlorine refers to the amount of chlorine in a sanitising product that is available to contribute to the Free Chlorine level.

Solid chlorine tabs contain a much higher (around 500 - 900 g/kg) concentration of available chlorine than liquid products (around 125 g/L) like sodium hypochlorite.

For this reason, solid disinfection products are more expensive, yet the required dose is much lower.

The available chlorine concentration is usually found on the product packaging.

How Much Sodium Hypochlorite (Bleach) Should I Add To Shock A Pool?

Sodium hypochlorite contains around 125 g/L of available chlorine, so you typically need to dose a fair bit to shock a pool properly.

As an example, for a 50,000 L pool with a combined chlorine level of 2 ppm, you would need to add 1.0 kg of available chlorine to achieve superchlorination.

Considering that bleach provides 125 g/L of available chlorine, you would need to dose 8 L to shock properly.

These figures can be confirmed in the calculator above.

What Products Are Supported In This Pool Shock Calculator?

This chlorine shock dose calculator allows you to enter a custom available chlorine concentration, so it can be adapted for use with any liquid or solid chlorine shock product.

If you aren't sure which product you are going to use, you can also select from a list of popular products, including:

• Calcium Hypochlorite
• Sodium Dichloroisocyanurate
• Sodium Hypochlorite (aka bleach)
• Trichloroisocyanuric Acid

Almost all chlorine products on the market consist of one of these chemicals. If you aren't sure which one to use, check out this guide on liquid vs solid chlorine.