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Everything you need to know about shocking your pool

By January 10, 2023May 10th, 2023Maintenance

What Does ‘Shocking’ a Pool Mean? How Long After Shocking Can I Swim?

You may have heard the term “pool shocking” when discussing your pool sanitization needs. Pool shocking refers to the chemicals you need to add to your swimming pool water to increase the chlorine levels and kill off bacteria and algae.

Pool sanitization works on two levels. On one hand, you need to constantly and consistently balance your chlorine levels and keep all chemicals in perfect equilibrium. On the other, you must make weekly adjustments to ensure your chlorine is efficient in destroying bacteria and algae.

That’s where pool shocking comes into place.

After heavy use or following a strong rainstorm, your pool chemicals may be out of sync. You need to “shock” your pool to ensure that all bacteria and algae are killed and your swimming pool water is safe to use.

There are many ways to shock your pool. This guide will help you understand how to safely sanitize your pool water. If you’re looking to have the experts handle your pool maintenance, you can always call Waterside Poolscapes and our maintenance crews will take care of all your swimming pool needs.

Pool Chemicals and Chlorine Levels

Pool water is stagnant, which means that you need to sanitize it to keep it clear, fresh-looking, and suitable for swimming.

Three Types of Chlorine to Monitor

There are three types of chlorine you need to keep an eye on:

  • Free chlorine (FC) is chlorine that circulates and kills bacteria and algae. Free chlorine levels should be between 1 and 3 ppm.
  • Combined chlorine (CC) is made of chloramines—compounds formed when chlorine meets ammonia. Ammonia is produced in the body and expelled along with byproducts such as sweat and urine, so it is easily found in swimming pools. Combined chlorine levels should be less than 0.2 ppm.
  • Total chlorine (TC) is the sum of free chlorine and combined chlorine.

What Happens When Combined Chlorine (CC) Increases?

Have you ever passed by a swimming pool and got a strong whiff of chlorine? This is a tell-tale sign that combined chlorine (CC) levels are elevated.

When the levels of your swimming pool CC levels go beyond 0.5 ppm, chlorine in the water struggles to kill off bacteria. The water is not properly sanitized and poses a risk to swimmers’ health.

That’s when you need to shock your pool. Shocking liberates free chlorine to do its job and kill harmful agents in the water.

How Often Do I Need to Shock My Pool?

You can either shock your pool preemptively or when chlorine levels get out of sync.

Shock Once per Week during Swimming Season

To maintain your pool in the summer, we recommend you shock your pool once per week. Summer is peak swimming pool season, so many people enter the pool and the chlorine in the water becomes less effective.

We also suggest you shock your pool when you open for the season and before closing it, to ensure optimal water health.

Shock after Rain

Pool shock is advised after a heavy rainstorm. Too much water in the pool decreases the efficiency of chlorine because it’s more diluted.

Shock to Combat Algae Growth

If you see signs of algae growth in your swimming pool, you must shock it with chlorine chemicals right away to kill the algae bloom and stop it from taking over your pool.

Shock after a Pool Party

If you love organizing swimming pool get-togethers, remember to shock your pool after each party. When many people use the swimming pool, they inevitably leave behind residual chemicals such as nitrogen and ammonia. These bind to the chlorine, create chloramines, and increase CC levels.

Shock after Extended Sunshine

Sunshine can destabilize chlorine levels and make your sanitizing chemicals less active. If the forecast predicts very hot and sunny days ahead of you, schedule a pool shocking session to make sure your pool is safe for swimming.

What Do I Use for Pool Shocking?

For pool shocking, you can use either chlorine or non-chlorine chemicals:

  • Calcium hypochlorite is a non-stabilized chlorine compound you can use to shock your pool.
  • Sodium dichlor is stabilized chlorine and doesn’t degrade with sunlight.
  • Potassium monopersulfate is a non-chlorine pool shock chemical that helps existing chlorine become more efficient by unbinding it from nitrogen and ammonia molecules.

The choice of shock product depends on the levels of combined chlorine in your swimming pool and the overall chemical balance of the water.

For example, calcium hypochlorite acts slowly and is calcium-rich. If the water is already high in calcium, its hardiness will increase after the pool shock.

Likewise, potassium monopersulfate doesn’t kill bacteria and algae but pushes existing chlorine to work better. Its greatest benefit is that you can swim in the water half an hour after treating it, unlike chlorine-based chemicals where you must wait for 24 hours before jumping into the pool.

Of course, if you’d rather not handle such chemicals yourself, you can let the maintenance professionals at Waterside Poolscapes take care of shocking your pool.

How Much Pool Shock Should I Use?

It is generally advised to raise the free chlorine levels to 10 times the combined chlorine level. The lower the CC level, the cleaner your pool, so don’t wait until it gets too elevated.

If you see that your CC level is starting to rise, act immediately. This way, you will need less pool shock and the treatment will be more effective.

How Long Before I Can Swim in the Pool?

If you use chlorine pool shock, you must wait for 24 hours before you jump into the water, as elevated chlorine levels can irritate your skin and your eyes. You may also experience breathing problems as you inhale the chlorine gas by-products before they have completely dissolved.

People with skin conditions such as eczema and psoriasis may witness worsening of their skin conditions when they come in touch with elevated chlorine levels.

If you choose a non-chlorine pool shock, you only need to wait 30 minutes to an hour before jumping into the water.

When Should I Shock My Swimming Pool?

Chlorine reacts with sunlight and becomes less efficient as it gets destabilized by sun rays. Therefore, it is best to use the pool shock late in the evening and let it act during the night.

As a bonus, you won’t have to stay away from your pool too long since part of the required 24-hour waiting period—if you use chlorine chemicals—will be during the night anyway.

I Want a Maintenance Crew to Shock My Swimming Pool

We get it, you want to enjoy your swimming pool without having to worry about the maintenance that comes with it. Waterside Poolscapes offers pool maintenance from our expert crews. Give us a call on 281-690-4810 and we will give you peace of mind and a perfectly sanitized swimming pool for you and your family to enjoy!