How Long Should You Wait to Swim After Shocking Your Pool?
Before diving into the pool, it’s important to make sure it’s safe first. And no, we’re not just talking about scanning the area for visual hazards — we’re also talking about ensuring the safety of the water. Obviously, changes in water color or clarity are a good indicator that something is “off” and your water isn’t safe for swimming. But the only way to know for sure is to test the water and check water balance and sanitizer levels. Shocking the pool is a crucial step in maintaining sanitary water, but many pool owners are unsure about the waiting period following a shock treatment. So, how long after shocking a pool can you swim? We’re glad you asked!
The Importance of Shocking a Pool
Maintaining a clean, safe, and beautiful pool is essential for both aesthetic appeal and swimmer safety. Regular pool maintenance includes things like regular cleaning, sufficient circulation and filtration, and maintaining proper water chemistry — which includes daily chlorination and weekly shock treatments. While all of these play a key role in keeping the pool water clean and clear, shocking is an important step that helps eliminate harmful bacteria, algae, and other contaminants that may be present in the water.
Treating the water with pool shock also helps break down inorganic chloramines, which form when your “working” chlorine, also known as Free Available Chlorine (FAC), react to and combine with nitrogen and ammonia from sweat, body oils, sunscreen, cosmetics, and other contaminants that accumulate in your pool water — ultimately decreasing the chlorine’s ability to sanitize your pool water. Chloramines can be problematic because they emit a distinct strong and unpleasant chlorine-like aroma around the pool, and are often irritating to swimmers’ skin and eyes. The best way to break down existing chloramines, or help prevent them from forming in the first place, is to shock the pool on a regular weekly schedule.
BONUS TIP: The type of shock you need depends on which primary sanitizer you use, how the water is balanced, and how much FAC is already in the water. In general, you’ll want to use a chlorinated pool shock if FAC levels are below 2 ppm, and you can use a non-chlorine pool shock if levels are above 2 ppm. To learn more about the different types of pool shock, check out our Resource Center article.
Factors That Affect the Wait Time After Shocking a Pool
Can you swim after shocking the pool? Yes…eventually. Instructions for wait times are listed on the product label, but the exact waiting period after shocking a pool is influenced by several factors. These include things like the type and strength of shock treatment used, the size of the pool, the dosage used, and current water conditions. Let's take a closer look:
1. Type and Strength of Shock Treatment
Different shock treatments have varying compositions and concentrations of active ingredients. The type and strength of the shock treatment used can affect how fast the product will integrate with the water and how quickly chlorine levels in the water will return to a safe range for swimming.
2. Size of the Pool
The size of the pool directly impacts the time it takes for the shock treatment to disperse and the chlorine levels to stabilize. Larger pools with a greater water volume require more time for the shock treatment to fully integrate with the water and disperse throughout the pool. Keep the pool pump running on high speed when adding any type of pool shock or water balancing chemicals to ensure optimized distribution throughout the pool and avoid “hot spots,” which are areas of concentrated chemicals that can harm swimmers and damage pool surfaces.
3. Shock Dosage
Speaking of pool size, the amount of shock you add will also play a role in total wait time required. The higher the dose per volume of water, the higher the chlorine levels will rise. Thus, the longer you’ll have to wait before you can hop in the pool again. When superchlorinating the water, such as when knocking down an algae bloom, you'll wait much longer than you would with a routine weekly shock treatment.
4. Current Water Conditions
The initial condition of the pool water can also influence the waiting time after shocking. If the pool water is heavily contaminated, extremely cloudy, full of algae, or imbalanced, it may take longer for the shock treatment to restore water clarity and safety.
BONUS TIP: There are many reasons why a pool might turn cloudy, and a low sanitizer level is just one of them. Learn more about the most common causes of cloudy pool water — and how to clear the water up quickly — in our Resource Center guide.
What’s the Recommended Wait Time After Shocking a Pool?
While the specific wait time after shocking a pool can vary widely depending on the factors mentioned above, a general guideline when superchlorinating the water is to wait at least 24 to 48 hours before taking a dip. This allows sufficient time for the shock treatment to disperse, the water to be thoroughly sanitized, and chlorine levels to stabilize within the ideal range of 1–4 ppm. Chlorine-free oxidizing shock is different, however, in that you usually only need to wait about 15 minutes before swimming can resume.
No matter which shock type you use, it’s essential to ALWAYS follow the instructions provided on the packaging, as different products may have specific recommendations for waiting times.
Testing the Water After Shocking a Pool
To ensure the pool is safe for swimming after you shock it, it's important to test the water. Before jumping in the pool, ensure the chlorine levels are between 1–4 ppm. Remember that elevated chlorine levels may throw off other water chemistry readings, so wait until your FAC level is back in range before worrying about the other test results.
If the chlorine levels are too high, you’ll need to wait a little longer before jumping in the pool. On the other hand, if chlorine levels are too low, you’ll need to treat the water again. There are a few causes for low chlorine levels after shocking the pool. The most common reason is that you may not be adding enough daily sanitizer, or you may not have added enough shock to the water. If neither of these are the issue, you may have a problem with heightened chlorine demand in your pool. In either case, an extra shock treatment is strongly recommended to ensure well-sanitized pool water that’s safe for swimming.
At-home test kits and test strips allow you to quickly measure FAC levels, pH balance, and other important chemistry parameters. But for a more comprehensive look at the chemistry levels in your pool, Leslie's can help with a FREE in-store AccuBlue® water test. In just 60 seconds, you'll get precise results for 10 different aspects of water chemistry, plus a customized step-by-step water treatment plan based on your test results. AccuBlue water testing can be helpful for troubleshooting recurring water quality issues, but it's also a great tool for keeping a close eye on the health of your water.
So, how long after shocking can you swim in your pool? The best bet is to always read and follow product label instructions. Wait times vary depending on product type, chlorine strength, shock dosage, and the overall condition of your water before and after shocking. When using chlorine-free shock, you can swim in as little as 15 minutes. But with chlorine pool shock, such as cal-hypo or dichlor, it’s important to test the water before swimming to make sure chlorine levels are within the ideal range of 1–4 ppm. When superchlorinating a pool, this usually takes at least 24 hours or more. If you’re only adding a lesser amount of shock to give FAC levels a small boost, it may not take as long. Again, the product label will include everything you need to know about the products you’re using.