Mr Pool Man's In-Depth Resource for All Things Pool

How To Shock A Pool


You should shock your pool every week or two with the correct amount of shock, but what is shock?


"Shock Treatment - The addition of an oxidizing compound or a mixture of oxidizing compounds to the water to destroy chloramines and other undesirable compounds.

– Bioguard


When you add chlorine to your pool, the chlorine molecules attach themselves to bacteria and other unwanted material, and it forms a chloramine. Chloramines are essentially dead chlorine. They do nothing and you should get rid of them – this is where shock comes in.

Shock oxidizes the chloramines turning it into a gas. When you smell chlorine, you are smelling chlorine that is NOT in the water because it’s oxidized.

Now that we’ve given you the reason on WHY you should shock your pool, let’s talk about how to shock your pool.


3 Types of Pool Shock

There are 3 different types of pool shock on the market today:


• Calcium Hypochlorite Shock (granulated chlorine, not sold online)


Lithium Hypochlorite Shock


Potassium Peroxymonosulfate (non-chlorine shock)


It is important to understand the difference between these 3 types of shock, as they all work differently.


Calcium Hypochlorite

This is the most popular chlorine pool shock. It contains about 65% available chlorine and is cheaper than the rest. When adding to the water, you must first pre-dissolve each pound in a 20L bucket of water to prevent bleaching. This type of shock is slow dissolving, so it will not completely dissolve before it hits the bottom of the your pool. Once added, you will need to wait 8 hours before swimming.


  • 65% chlorine

  • Pre-dissolve required

  • 8 hour wait time

  • Adds calcium to the water

  • Add at night


Lithium Hypochlorite

This type of shock is commonly used in areas that have a high amount of calcium in the water since this shock doesn’t use calcium. It contains about 35% available chlorine and is more expensive than using calcium hypochlorite. The one positive is you don’t have to pre-dissolve this type of shock, but you still need to wait 8 hours before swimming.

• 35% Chlorine

• No pre-dissolve

• 8 hour wait time

• Add at night







Potassium Peroxymonosulfate (non-chlorine shock)


Non-chlorine shock is typically used in bromine pools, but you can use it in chlorine pools as well. You do not need to pre-dissolve and it only takes 15 minutes before you can swim again.

• No chlorine

• No pre-dissolve

• 15 minute wait time

• Add anytime






How to Shock a Pool: Quick Tips

  • Always use gloves and protective eye wear.

  • Add 1 pound of shock a 20L bucket of water about 3/4 full.

  • Always add shock to water not water to shock.

  • Wear clothes you don’t care about – they might get bleached.

  • Warm water dissolves shock faster than cold.

  • DO NOT add shock directly to your skimmer!

  • Use a wooden stick and slowly stir in the shock making sure it dissolves completely, or as much as possible.

  • Slowly pour the bucket of pre-dissolved shock around your pool. You may have some undissolved shock at the bottom of your bucket. In this case, just dip your bucket in some pool water give it a slow swish around and pour it back into the pool to help dissolve some of that shock.

  • DO NOT mix all the bags together in one bucket.

  • Always shock at dusk or night time. The chlorine works better when it’s not being burned off by the sun.

  • Shock should also be added every week to ensure a clean and algae-free pool.


Happy Swimming!

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