Last Updated on August 23, 2020
Swimming in a recently shocked pool can be dangerous. How dangerous it can be is determined from the type of pool shock chemicals you use and how much you use.
The level of danger is also based on how long you wait before entering the pool after treatment.
There are a few standard pool shock chemical products that residential and commercial pools use. In this article, we discuss the different types of pool shock chemicals, the warnings that come with each, and how dangerous it can be to swim in a recently shocked pool.
What is pool shock?
Pool shock is a mixture of chemicals that are added to a pool to kill algae and bacteria. There are different types of pool shock chemical compounds that are used for different circumstances, and some are more dangerous than others. You should take caution when using any pool shock and read the warnings on every pool shock treatment package before using it.
Pool shock treatments are necessary to keep swimming pools safe from algae and bacteria. However, you also need to make sure you wait for the determined amount of time before entering your pool after shocking it. Otherwise, it can present even greater health dangers. Let’s discuss the common warnings and risks of chemical shock treatments.
Common dangers presented in chemical shock treatments:
- Common miscellaneous risks: Contamination or improper use may cause fire, explosion, or the release of toxic gases. Treatment is highly corrosive. Will cause skin and eye damage. May be fatal if swallowed.
- If this treatment gets in your eyes: Hold eye open and rinse slowly and gently with water for 15-20 minutes. Call a poison control center or doctor for treatment advice.
- If this treatment gets on your clothing: Take off contaminated clothing. Rinse skin immediately with plenty of water for 15-20 minutes. Call a poison control center or doctor for treatment advice.
- If this treatment is swallowed: Call a poison control center or doctor immediately for treatment advice. Have a person sip a glass of water if able to swallow. Do not induce vomiting unless told to do so by a poison control center or doctor. Do not give anything by mouth to an unconscious person.
- If this treatment is inhaled: Move the person to fresh air. If the person is not breathing, call 911 or an ambulance, then give artificial respiration, preferably mouth-to-mouth if possible. Call a poison control center or doctor for further treatment advice.
You must be careful when handling pool shock treatments. What is a regular occurrence in pool maintenance and safety can be a dangerous experience if not handled properly. Never touch the chemical substance without gloves. For protection, consider wearing safety glasses or goggles.
Besides the dangers with the handling of chemicals, consider what would happen if you entered a pool that was just shocked. If you don’t wait for the chemicals to dissolve, settle, and work properly, you could experience the same dangerous effects by swimming in a recently shocked pool.
How long do you wait to swim after shocking the pool?
How long you wait depends on the type of chemical that is used and how much of it is used in relation to the size of your pool. The best way to know precisely when it is safe to enter the pool again is by using test strips that measure the chemicals.
Most Common Pool Shock Substances
The following sections will discuss the chemicals involved in the most common pool shock substances and the general time it takes for each to work.
Cal-Hypo Pool Shock
- SIGNATURE REQUIRED AT TIME OF DELIVERY
- 70% available chlorine, Pool Shock and Super Chlorinator
- Fast dissolving granular formula
- 1 lb will provide 2ppm of available chlorine in 40,000 gallon pool
Calcium Hypochlorite (abbreviated “Cal-Hypo”) is the most common chemical pool shock used to disinfect both residential and commercial swimming pools. This shock treatment kills algae and bacteria that begin to grow in your pool. Most cal-hypo pool treatments contain 65% or more chlorine.
Some brands instruct users to dissolve the substance before adding it to your pool while others explicitly state not to. It is best to follow the instructions on the label of the pool shock treatment you are using.
This shock treatment must be used after dusk. The problem with using it during the day is due to the sun. The heat from the sun will burn the chemical substance before it can do its job. Although this will show lower chemical levels faster, it won’t be because of the chemicals doing their job to kill bacteria and algae. Instead, it will be because the sun burned it.
Each pool shock substance has its own time estimation for safety. It’s always best to use a test strip to ensure the pool’s chlorine level is safe before entering. The average time before safely entering the pool is 8 hours. Shocking your pool before bed will commonly allow you to safely swim again the next morning.
- In the Swim's granular chlorine is ideal for use in swimming pools, spas, fountains and water features
- Powerful sanitizing powder that destroys bacteria, breaks down contaminants and kills algae
- Calcium-Free formula keeps hard-water pools sparkling clean and crystal clear
- Contains premium-quality 56% available stabilized chlorine
Dichloroisocyanuric acid (commonly abbreviated “Dichlor”) is also used as a chemical pool shock treatment mostly for residential pools. It is used for chlorine doses as well as shock treatments and contains less chlorine than the Cal-Hypo treatment at around 50% chlorine.
Like Cal-Hypo, some brands recommend dissolving it before adding it to your pool while others specifically instruct users to dump it right in their pool without dissolving. Follow the instructions on your chosen pool shock for safety.
This pool shock treatment must also be used after dusk for the same reasons. The chlorine in this treatment will burn away from the sun during the day before it can do its job of killing bacteria and algae.
Each brand of Dichlor pool shock is different but similar to Cal-Hypo, the average wait time before safely re-entering your pool is about 8 hours.
- Economical 6 lb. Pail with Carry Handle & Child-Resistant Lid
- Granular Monopersulfate Oxidizing Shock - Highest Active Oxygen
- Unsurpassed quality - Equals or outperforms all other brands
- Maximum effectiveness in pools and hot tubs
Non-chlorine pool shock treatments are used by those who want to be able to swim soon after treating their pool. The most common ingredient in non-chlorine pool shock treatments is potassium monopersulfate, and this shock treatment contains NO chlorine.
What many like about this type of treatment is that they can add it directly to their pool day or not without mixing. The sun doesn’t burn up the active ingredient like it does chlorine.
Instead of waiting eight hours for safe swimming, you only have to wait about 15 minutes before re-entering your swimming pool.
The drawback of using non-chlorine shock is that because there is no chlorine in the ingredients, it doesn’t work as well on algae. Some users of non-chlorine pool shock claim less than desirable results while others stand by this as their only shocking solution.
I would recommend only using a non-chlorine shock treatment when you want to be able to swim again shortly after. Once night comes, go back to your chlorine shock treatment.
The type of shock treatment you use in your pool and the amount of time you wait will determine what happens if you swim in a shocked pool.
If it were shocked ten hours ago with the correct ratio of treatment to pool size, it would probably be okay to swim. Test strips are the best way to be confident about the safety of re-entering the pool after pool shocking.
If you enter the pool immediately following a chlorine pool shock treatment, you are risking as little as skin and eye irritation and as much as fatality. Shocking your swimming pool is necessary, but take caution when doing so.