Know when to Shock your Swimming Pool (2)

(Sources of the Information: All the information included in this post are based on knowledge from my Barack James profession as a chemical engineer, personal working experience of more than 7 years, and standard rule and regulations by relevant bodies)

+Barack is a chemical engineer and pool water chemistry nerd: He has been in commercial pool maintenance industry for more than 7 years!


What is the Best Time to Shock a Swimming Pool?

Ultra violet (UV) light from direct sun greatly affects chlorine effectivity in the swimming pool. As such, the best time of the day to shock a swimming pool is in the evening when the sun has gone down, to protect free chlorine from UV light from direct sun.

Which Chlorine Pool Shock is the Best for my Non Saltwater Pool?

Basically, there are 4 types of chlorine pool shocks available in the market: Each pool shock comes with its own pros and cons. The type of pool shock to use in your pool will depend on your pool requirements and some other factors.

Below is more detailed information on different pool shocks available, you can use this information to decide which pool shock chemical is the best for your pool and why it is the best.

1. Calcium Hypochlorite Pool Shock

Calcium hypochlorite is the cheapest type of chlorine shock available in the market.

This pool shock has the highest chlorine percentage (65%) amongst all chlorine pool shocks.

Use calcium hypochlorite if you need to add calcium into the pool water. It needs to be pre-dissolved before it is used to shock the pool.

Use it at night or in the evening to protect free chlorine from UV light from the sun.

Also important, you need to wait for 8 hours before using the pool when you use calcium hypochlorite to shock a pool.

2. Lithium Hypochlorite Pool Shock

Lithium hypochlorite has the lowest percentage of chlorine (35%) and the most expensive type of pool shock available in the market.

To use lithium hypochlorite, you don’t need to pre-dissolve it like calcium hypochlorite needs.

Use it at night or in the evening to protect free chlorine from the direct sun light.

Lithium hypochlorite pool shock also needs that you wait for 8 hours before swimming in the pool.

3. Di-Chlor (Granular Chlorine) Pool Shock

Di-Chlor or granular chlorine pool shock has 60% chlorine concentration. This pool shock adds Cyanuric acid into the pool water and should be used with controlled amounts of Cyanuric acid in the pool.

Di-Chlor doesn’t need to be pre-dissolved in order to use it as a shock. Add it at night or in the evening to protect free chlorine from UV light from the sun. Wait for 8 hours before swimming in the pool.

4. Pottasium Peroxymonosulfate (Non Chlorine Pool Shock)

Pottasium peroxymonosulfate is a non chlorine pool shock, used mainly in Bromine swimming pools. However, it can also be successfully used in chlorine based pools.

Pottasium peroxymonosulfate doesn’t need to be pre-dissolved in order to be used as a pool shock.

On the positive side; you can use a swimming pool shocked with potassium peroxymonosulfate after only 15 minutes, unlike the rest pool shocks that have to be free of use for 8 hours.

Also, this pool shock can be added into the pool at anytime as it is chlorine free and cannot be affected by direct sunlight like the rest.


How to Shock a Non Saltwater Swimming Pool

Shocking or super chlorinating a swimming pool is not difficult and anyone can do it right when correct directives are followed. Here is an outline of all you need to do when shocking a non saltwater pool:

  • Prepare shock chemicals as required: depending on the shock chemical you use in your pool, some shock chemicals need to be dissolved before using in the pool. More details of 4 types of shock chemicals available in the market are discussed above.
  • Fill a bucket with 5 gallons of water from the swimming pool, which is about or equal to 19 liters of water.
  • Add the prepared pool shock into the bucket of water: Always don’t add water into the pool shock, but the other way round.
  • Stir the bucket well to mix the pool shock with water.
  • Pour the bucket of dissolved shock slowly around your pool.
  • Refill the bucket with water and stir again to dissolve left over shock chemical in the bucket and pour slowly again around the pool.
  • Leave the pool for recommended hours before swimming depending on the type of shock chemical you use.
  • Measure the amounts of chlorine to make sure it is 3 ppm or slightly less before swimming in the pool as it is dangerous to swim in a pool with high chlorine concentration. You can use chlorine reduction reagents when necessary.


As we have seen, to have a healthy pool water free of bacteria, algae and other organisms; there is no specific time frame set that is appropriate to shock a non saltwater pool: Rather, how frequent you need to shock your pool depends on a number of factors discussed above based on which comes first. On the other hand, make sure that you do enough research on pool shocks, to ensure that you use the best type chlorine shock in your pool to avoid extra expenses that comes with clearing contaminated, cloudy, green, or bacteria infected pool water.



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