Pool Shock vs. Chlorine: What’s the Difference?

Shock vs. Chlorine

Pool chlorine and shock are two chemicals that every pool owner will need at some point. Although they have the same active ingredients, they serve different purposes in swimming pools.

Chlorine sanitizers are the most commonly used compounds for pool maintenance, while shock deals with specific pool problems like chloramines.

That said, the difference between these two is in their strength, as pool shock is a more potent pool treatment than regular chlorine sanitizers.

What Does Shock Do?

The primary purpose of pool shock is to raise the levels of free chlorine in the swimming pool. It does this by introducing higher chlorine levels to the pool than what you get with regular chlorine sanitizer.

Pools shocks aim to get the free chlorine levels up to over 5 ppm for a few hours. Doing this ensures up to 10 times more free chlorine in the pool than combined chlorine, which destroys contaminants like chloramines, bacteria, and algae.

What Does Chlorine Do?

Regular chlorine sanitizers are for keeping the pool water clean and sanitized. They come in tablet, liquid, granular, or powder form, and they are added in small doses to keep the chlorine levels at the recommended 1 to 3 ppm-level.

Chlorine cleans and sanitizes the pool water continuously, provided there is enough of it in there. Also, it has oxidation properties that will help keep the pool water clear.

Shock vs. Chlorine


Both chlorine and powered shocks are unstabilized types of chlorine. Also, both have high enough levels of active chlorine to kill a wide variety of microorganisms and pool contaminants.

Similarly, they are effective at controlling algae and can help you clear out your cloudy pool through oxidation.


The main difference between the two is the dosage, as shocks will have a much higher concentration of chlorine than regular chlorine sanitizers since they need to raise the levels in the pool water fast.

Another key difference is that chorine is more of a residual cleaner, meaning that it will be added to the pool water slowly for continuous maintenance. Shock, on the other hand, is quick-releasing as it is intended to offer rapid sanitization.

The mode of application also differs. In most instances, you will need to first mix your shock with water before adding it to the pool water as it can cause staining given its high concentration. With chlorine sanitizers, pre-mixing is often unnecessary as you can add them directly to the pool water.

Bottom Line

Shock and chlorine are both essential chemicals for maintaining your pool, and it is almost certain you will need to use both at some point.

Chorine sanitizers are handy for regular pool cleaning and sanitization as they add just small doses of chlorine to the water. On the other hand, shock is crucial for raising the free chlorine levels fast when dealing with more severe issues like chloramines.

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