How Long After Shocking a Pool Can You Swim?

Dirty pools are unsanitary, bring down the overall environment, and can be a painful eyesore to anyone passing by. To ensure you’re maintaining the health and overall appearance of your pool to the public, or your neighbors, it is important to perform shock treatment maintenance weekly or twice a month. 

You should wait a minimum of 24 hours after shocking it before swimming in your pool. This is due to the high chlorine content in the pool, which can cause lung, skin, and eye damage to swimmers.  The chlorine levels should return to levels below three parts per million (ppm) before it is safe. 

What is Shocking a Pool?

“Shocking” a pool means you are chemically blasting the harmful bacteria and germs out of the water, sanitizing it for further use. A public pool has many visitors and swimmers, especially outdoor public pools, and they all bring bacteria, sweat, and germs to the pool environment. Your home pool is subject to the same contaminants when you, your family, and your friends use your pool.

The pool is also exposed to the natural environment, so as a result, unwanted hazardous materials such as algae and ground bacteria grow in the pool. You should clean or “shock” your pool often, based on weather conditions and how often the pool is used.

Regular cleanings will help you maintain a clean swimming environment for the public or those who use your pool. To shock a pool, you have to raise the free chlorine level to a more significant amount, roughly 10x the amount of combined chlorine available in the pool. At this point, the free chlorine can sanitize and eliminate contaminants from the pool environment, allowing you to enjoy a clean swimming experience without slimy algae and slippery pool floors. 

After doing this, you’ve reached “breakpoint chlorination” – a state where the free chlorine can disinfect the combined chlorine. Shocking your pool prevents infections and keeps everyone healthy.

How Long Should You Wait After Shocking a Pool?

It is best to wait at least 24 hours after you apply a shock treatment so that it has time to take effect before you enjoy your pool again. If you have a large algae bloom, you may need to shock for longer compared to a simple maintenance shock. 

First, it should be noted that shock treatment times vary based on the number of contaminants or algae in the pool. Once the pool shock treatment is applied, it will start to sanitize and eliminate harmful germs, bacteria, and algae buildup. 

Swimming in a freshly shocked pool has a spectrum of consequences, ranging from mild, to severe and even fatal. The chemical chlorine can irritate your skin, giving you chemical burns and lesions. The chlorine can also get into your eyes, causing them to be red, itchy, and irritated, and in worse case scenarios, lead to blindness. 

This is due to the chlorine chemical withdrawing water from your skin and disintegrating it between your skin’s layers. If you ingest the pool water, it goes into your body and into your digestive tract, where the chemicals are absorbed and processed. If there is too much chlorine in your system, you could end up terribly sick or permanently disabled.

When Should You Shock Your Pool?

If your pool is used often by friends and family, it is suggested that you shock your pool at least once every 1 to 2 weeks, to ensure the water is sanitized and not at risk of causing infection for you or your guests. If you take extra care of your pool, such as covering it up after each use, checking the regular filtration system daily, and clearing out any leaves or other debris – you may not need to shock as often as once a week.

Your pool takes in bacteria, urine, sweat, cosmetics, and other contaminants regularly, and will need to be cleaned often to maintain a clean swimming environment. Doing so will help your pool’s natural and daily filtration system work at its best, and provide less stress and strain on its overall system. During the winter seasons, you can take care of your pool by keeping it covered up, preventing a collection of fall leaves and fall grime from making the stagnant water worse. 

 Pool shock maintenance needs are based on the level of upkeep the pool undergoes, and local weather conditions. But, as a safety net, once every 2 weeks should be enough to keep your pool environment healthy and sanitary.

How to Shock a Pool?

To shock a pool, you will need protectant gloves, protective eyewear, spare paints, a long-sleeved shirt, a liquid testing kit or ph kit, pool shock, a 5-gallon bucket, and a stir stick. The shirt you wear must be long-sleeved to avoid chemical irritation if any pool shock chemicals happen to get on you in the process. The gloves and glasses will also protect you from chemical irritation during the mixing process. 

Step 1: Test the Water

First, you have to test the pool water. The free chlorine level should be lower than the total chlorine level – showing that your pool needs to be desensitized. To do this, you can use pool water test strips. 

Gather your test strips, and use a cup to collect a small and portable sample of your pool’s water. Use the cup to gather your sample, and open the test strips. 

Dip one test strip into your sample cup, and await the results. If the free chlorine level is lower than the total chlorine level, it is time to shock your pool. 

If you would like to know how to properly chlorinate your pool check here.

Step 2: Calculate How Many Chemicals You’ll Need 

You will need to calculate how many chemicals are needed for your pool shock treatment. To know how much chlorine shock treatment powder to use, you need to know the volume size of your pool in gallons. Use that measurement to determine how much shock to use, usually listed on the shock product you buy in commercial stores. 

To determine volume, you can ask the company that built your pool, use an online calculator, or get the dimensions yourself. 

L x W x Average Depth x 7.5 

L = Length of pool

W = Width of pool Average Depth of pool = shallow end depth + deepest end depth / 2

Example: 5ft long pool, 8 feet wide pool, is 8 feet at deepest end and 2 feet at the shallow end. 

Average depth = 8+2/2 = 5 

5 x 8 x 5 x 7.5= 1500 gallons

Step 3: Mix Pool Shock With Water

Now, it’s time to mix the pool shock with water.  To do this, you should first put on your gloves and glasses to protect your eyes and hands from skin irritants in the shock chemicals. 

Gather up your bucket, stir stick, and chlorine shock mix. Add however many cups of the shock chemicals your pool’s measurements call for based on volume, into the 5-gallon bucket. Be sure to add the correct amount needed for your pool’s chlorine mixture to reach the breakpoint. 

Add water, then stir, being careful to avoid skin contact. Once dissolved, let the mixture sit for a minute. 

Step 4: Pour the Shock Into the Water

Now it’s time to pour your shock mixture into the water. Being careful, grab the 5-gallon bucket with your gloves on, and slowly pour the mixture into the pool while walking around the edge. 

Keeping your gloves on is important while doing this because there will be splashes of treated water flying close to your hands. If your mixture has solid particles inside, dip the bucket into your pool and swish it around vigorously to dissolve the mixture into the pool. 

After you’ve poured your mixture into the pool, remember to check your filter and remove any debris blocking it. This can ensure the pool’s filter and pump are running effectively, making the shock treatment run more thoroughly. 

Step 5: Keep Pool Pump Running

After you’ve poured your mix in and ensured your pool’s filter is cleared of debris, you want to make sure your pool’s pump is on and running at maximum speed. This is to ensure that the shock mixture you’ve recently poured in, is mixed into the pool’s water effectively. 

The pool’s pump will assist in mixing the shock in more thoroughly than without it. You want to have your pool’s pump running after treatment, for about 8-12 hours. 

It’s important to note that if you don’t run your pool’s pump during a shock treatment, you run the risk of bleaching your pool’s floors and walls. Having the pool’s pump running assists in removing the treated water and excess debris from the pool leaving the pool’s walls and floors free from the bleach.

Step 6: Test the Pool Again

After treatment, you want to test the water again. It’s important to check the water again, especially if you treated a heavily covered algae pool, to ensure that the water’s chlorine levels aren’t too high. You don’t want the chlorine levels to be too high in the pool because it’s a skin irritant. 

Using a test strip, you can check the free chlorine levels vs the combined chlorine levels, ensuring a clean balance. You’ll also be able to check to ensure the chlorine level in the pool is at least 3 ppm. 

If the pool is still dirty, showing more combined chlorine compared to free chlorine, you’ll have to treat it again and wait another full 24 hours. 

What Type of Chlorine Should You Use? 

There are four types of pool shock you can use: Calcium Hypochlorite, Lithium Hypochlorite, Dichlor shock, and Non-chlorine shock. We know we need to use chlorine to shock the pool, but it might help if we got a better idea of what kind of chlorine to use, and the differences between each kind. 

Chlorine Shock

Calcium Hypochlorite

  • Most calcium hypochlorite has to be mixed, and dissolved before use to treat a pool.
  • Must be used after dusk.
  • The wait time after treatment is about 8 hours.

Lithium Hypochlorite

  • Must be used after dusk, when the sun is down.
  • Wait time after treatment is about 8 hours
  • Is toxic to aquatic life, therefore a great algaecide, however, you should take care when disposing of recently treated waters

Dichlor

  • Does not need to be dissolved ahead of time.
  • Must be used after dusk, when the sun is down
  • Wait time after treatment is roughly 8-9 hours

Non-Chlorine

This can be added to your pool water at any time. The wait time for this treatment is 15 minutes.

It is non-chlorine based, so will not work to eliminate algae. 

The type of shock you need to use is based on the sanitization needs of your pool. If your pool is experiencing a major algae bloom, then Calcium Hypochlorite is a better option for your pool compared to the Non-Chlorine based option, which is best suited for saltwater pools. 

Conclusion

No one wants to swim in a nasty, algae-infested pool. The feeling of stepping into a cool, clean freshwater pool during the summer is unmatched. 

You must take care of your pool, providing it with regular shock treatments. Always wait 24 hours before swimming in your recently treated pool. Remember, if you’re ever unsure of the water’s chlorine levels after a treatment, you can check the pool’s Ph balance to see that the chlorine levels are at 3 ppm. 

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