How Long to Wait After Shocking a Pool? - Sutro, Inc

How Long to Wait After Shocking a Pool?

Maintaining a clean, safe, and healthy pool is essential for all pool owners. Adding a shock is one of the pool maintenance routine's most basic and crucial parts. Plus, one has to wait for some time before being able to use the pool again. This duration depends on various factors, such as the strength and type of the shock treatment, the pool's size, and the water chemistry before shocking.

Here, we'll discuss essential insights to help you understand how long to wait after shocking a pool. Let's start with the basics:

What do you mean by shocking a pool?

Shocking a pool refers to adding sanitizer (Chlorine or bromine) to your pool. It will kill algae, bacteria, and other harmful microorganisms in the water to keep it clean and safe for use. It also replenishes the supply of available active sanitizer in the water.

However, pool owners must consider factors like pool size and the current water chemistry to evaluate the right amount of shock.

When should you shock your pool?

Shocking a pool can be seen as routine maintenance work of your pool and should be done regularly (once or twice a week). However, it becomes essential sometimes, such as after heavy rain or a pool party. Check this list below to name a few:

  • Whenever you open or close your pool
  • If you have thrown a pool party (heavy bather load)
  • Too many leaves or debris has fallen into the pool water
  • Before adding any other chemicals to the pool (so the water has optimal sanitizer levels)
  • Shocking the pool right after heavy rain or thunderstorms would be great
  • If you see any green or pink algae or the water has turned cloudy and/or smelly, it is already high time to shock your pool.

Apart from all these considerations, the best method is to check the water chemistry of your pool water routinely. Correct monitoring of the sanitizer levels will ensure you don't add too early/late or too much/less.

If routine pool water monitoring seems challenging, you can conveniently use a digital pool monitoring system. For example, our Sutro pool monitoring system offers real-time water chemistry analysis on your mobile app and personalized recommendations on when to shock your pool.

What type of shock can you use?

You have a few different options to shock your pool. The most common shock types are:

Calcium Hypochlorite Shock (Chlorine Shock):

Also known as cal hypo, it contains Calcium Hypochlorite - a highly active form of Chlorine for killing algae and bacteria from your pool. It is the most potent and quickest chlorine shock available for outdoor or indoor pools and also the most common one.

Non-Chlorine Shock:

A non-chlorine shock is a chemical compound called Potassium Peroxymonosulfate that works like Chlorine and oxidizes the organic contaminants from your pool. If you are one of those pool owners who like to keep their pool chlorine-free because you are sensitive to its odor, this shocking treatment is definitely for you.

Dichlor Shock:

It uses Dichloroisocyanuric acid, which is Chlorine in its stabilized form. It releases cyanuric acid into the pool water, preventing the Chlorine from oxidizing quickly under sunlight. Hence keeping the sanitizer levels up for longer.

Dichlor shock is suitable for pool owners who do not have the time to shock the pool frequently.

Note: Pool owners should also remember to follow all the safety measures and dosage instructions for shocking treatment to work correctly.

Can I swim 12 hours after shocking the pool?

Depending upon the pool size and type, 8-12 hours is sufficient in most cases, but one should consider taking enough time for the shock to get cleared from the water. The best way to ensure the chemical levels have returned to normal is to do a quick check using a pool test kit or a digital system like our Sutro Pool Monitor.

In case if you get into the pool before the chemicals have dissolved - it might result in mild or severe health problems like eye irritation, chemical burns, and even respiratory issues. Hence it would be wise to wait at least 12 hours after shocking the pool.


Maintaining optimal levels of sanitizer in the water protects against most upcoming problems with water chemistry. You should wait 8 to 24 hours before reentering the pool. Although, the best method is to test the water chemistry and ensure the Chlorine is below 5 ppm and the pH is close to 7.5.


Here's a small set of frequently asked questions about shocking your pool.

Should you shock the pool during the day or night?

Shocking the pool at night would be ideal because the sun can deplete the Chlorine during the day, resulting in a less effective pool shock treatment. Moreover, shocking the pool at night will give you more time to let the water properly circulate and absorb the sanitizer.

Should you run the pool pump when shocking?

Keeping the pump running when shocking your pool would allow the water to circulate properly for maximum effect.

What are the optimal levels of Chlorine in a pool?

The optimal levels of free Chlorine should range between 1 to 3 ppm.

How long to wait after shocking the pool to add other chemicals?

After shocking the pool, you must wait at least 24 hours to add other chemicals. This allows Chlorine levels to return to normal and not interfere with other chemicals.

Back to blog