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How to Shock a Swimming 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.

4 Types of Pool Shock

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

It is important to understand the difference between these 4 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 5 gallon 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

In The Swim Chlorine Pool Shock 24 X 1 lb. bags

List Price:
Price: $59.99
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A very effective pool shock that uses calcium hypochlorite (chlorine) to instantly kill bacteria in your swimming pool.

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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

In The Swim Lithium Pool Shock 24 lbs

List Price:
Price: $172.99
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A very effective pool shock that uses lithium hypochlorite to instantly kill bacteria in your swimming pool.

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Di-Chlor (Grandular Chlorine)

Grandular chlorine is simply 60% chlorine that you can pour directly into the water. You will need to wait 8 hours before swimming again, but no need to pre-dissolve and it contains cyanuric acid (chlorine stabilizer) that protects the chlorine from being burned off by the sun. It’s more expensive than calcium hypochlorite, but you can use it for regular chlorine dosages and shock treatments.

  • 60% chlorine
  • No pre-dissolve
  • 8 hour wait time
  • Adds cyanuric acid to the water
  • Add at night

Nava 1-1301-24 24-Pack Chlorinating Shock Treatment for Swimming Pools, 1-Pound

List Price: $119.99
Price: $101.47
You Save: $18.52 (15%)

A very effective pool shock that uses di-chlor to instantly kill bacteria in your swimming pool.

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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. However, this type of shock can get very expensive.

  • No chlorine
  • No pre-dissolve
  • 15 minute wait time
  • Add anytime

In The Swim Chlorine-Free Pool Shock - 24 x 1 lb. bags

List Price:
Price: $68.99
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An effective pool shock that allows you to swim 15 minutes after shocking.

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How to Shock a Pool: Quick Tips

  • Always use gloves and protective eye wear.
  • Add 1 pound of shock a 5 gallon 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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  • Miriam Druyan

    I have to say thank you for your whole site and the newsletter – they were helpful last summer, and I’m now ‘studying up’ for this summer! Question – we have a 3 meter Intex round pool. We keep it covered at night. The nights we shock it, though – keep it covered, or will it work better if the gas can escape more easily?

    • Matt Giovanisci

      On the nights you shock, keep the cover off.

      Glad you like the site and found it helpful :-)

  • aaron

    Hi Matt: What about using liquid chlorine to shock the pool? I am a total newbie!