How to Chlorinate a Pool

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Chlorine helps keep a pool clean, and managing chlorine levels is an important aspect of owning a pool. Chlorine tablets are the best option for maintaining a normal level of 2 to 3 parts per million (ppm). To distribute the chemical evenly, add the tablets to an automatic dispenser. In addition to using tablets, you should also sanitize your pool with a liquid or granular chlorine shock treatment every 1 to 2 weeks. Whether you’re working with chlorine in tablet, liquid, or granular form, read the product’s instructions carefully and use it as directed.

Method 1
Method 1 of 2:

Maintaining Normal Chlorine Levels

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  1. Put on a pair of protective goggles and thick gloves before working with chlorine and other pool chemicals . If you’re treating an indoor pool, make sure there’s adequate ventilation before opening a chemical container. [1]

    Safety Tip: Be especially cautious if you're using a liquid or granular product. Wear long sleeves and pants, and be careful not to spill the chlorine.

  2. Tablets are the most popular way to chlorinate a pool. They’re easier to use, last longer, and are gentler on pool liners than liquid options, which are best used as shock treatments. Unlike granulated options, tablets dissolve slowly, which ensures even distribution. [2]
    • Purchase chlorine tablets online or at a pool supply store. Tablets come in 1 inch (2.5 cm) and 3 inches (7.6 cm) sizes. The larger tablets are the preferred option. They’re easier to handle, last longer, and are generally less expensive than 1 inch (2.5 cm) tablets.
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  3. Calculate your pool’s volume if you don’t already know it. You’ll need to know how much water your pool holds in order to determine the right amount of chlorine to add. For a quick estimate, measure your pool’s length and width, find the average depth, then multiply length by width by the average depth. If your pool is circular, measure the diameter, divide that value by 2 to find the radius, then use the formula πr 2 h , where r is the radius and h is the average depth. [3]
    • Suppose you have a 50 ft × 20 ft (15.2 m × 6.1 m) pool. If the shallow end is 3 ft (0.91 m) deep and the deep end is 6 ft (1.8 m) deep, the average depth is 4.5 ft (1.4 m).
    • After finding the average depth, you'd multiply 50 × 20 × 4.5 ft (15.2 × 6.1 × 1.4 m) to find a volume of 4500 cubic feet (127 m 3 ). Since 1 cubic foot (0.028 m 3 ) contains 7.48 gallons (28.3 L) of water, your pool holds 33,760 gallons (127,800 L) of water.
    • You can also download an app or use an online calculator to find your pool’s volume.
  4. to determine how much chlorine to add. Before chlorinating your pool, test the pH and chemical levels using a pool water test kit. Read your product’s instructions; the label will let you know how much to add based on your pool’s volume to reach the target chlorine level in ppm. [4]
    • Your test kit will show multiple chlorine readings. Free available chlorine is active and kills germs, while combined chlorine is the amount that’s been used up killing germs. Test your pool water daily if it gets regular use, and maintain a free available chlorine level between 1 and 3 ppm. [5]
    • If you’re maintaining a spa or hot tub , keep the free available chlorine level around 4 ppm. [6]
    • Always round up to the nearest 5,000 gallons (19,000 L). For instance, suppose you have a 33,760 gallons (127,800 L) pool, your current chlorine level is around 0 ppm, and your product directs you to add 1 tablet per 5,000 gallons (19,000 L) to increase chlorine levels by 1 ppm. You’d need 14 tablets to achieve a reading of 2 ppm.
  5. Simply tossing tablets into the pool won’t do the trick. Instead, it’s best to use a floating chlorine feeder, chlorinating skimmer, or other automatic dispensing device. All you need to do is place the tablets in the feeder’s cartridge and allow them to dissolve, which usually takes a few days. [7]
    • Unless your pool’s chlorine level is below 1 ppm or above 5 ppm, it’s fine to go swimming while the tablets dissolve. They’re designed for routine, continuous use.
    • You can find chlorine dispensers online and at pool supply stores. Simple floaters are inexpensive, while skimmers that clean debris and dispense chemicals can cost hundreds of dollars (U.S.).
  6. Cyuranic acid is a stabilizer that makes chlorine last longer. If your chlorine is labeled “stabilized,” “trichlor,” or “dichlor,” it already contains cyuranic acid, and there’s no need to take any further action. If not, purchase liquid or granulated cyuranic acid, dilute it according to the package’s instructions, then add it to the pool. [8]
    • The right amount to add varies by product. In general, you’ll need to add about 4 pounds (1.8 kg) of cyuranic acid per 10,000 gallons (38,000 L) of water to reach a level of 10 ppm. It’s recommended to maintain a cyuranic acid level around 50 ppm.
    • Remember to wear goggles and gloves when you mix and apply pool chemicals.
    • Do not add cyuranic acid to a spa or hot tub.
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Method 2
Method 2 of 2:

Shocking Your Pool

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  1. While tablets are best for routine chlorination, shock treatments typically come in liquid or granular forms. Required amounts and application methods vary, so consult an employee at the pool supply store and read your product’s instructions carefully. [9]
    • In general, you’ll need 3.5 US quarts (3.3 L) of liquid shock treatment or 1 pound (0.45 kg) of a granular product per 10,000 gallons (38,000 L) of water.
    • To be sure, check the instructions for the amount needed to produce a 1 ppm change in chlorine levels. Your aim is to bring free available chlorine to at least 8 ppm.
  2. If necessary, fill a large, clean bucket with the amount of warm water called for in the instructions. Then add the recommended amount of chemical carefully to avoid spilling or dispersing fumes. Slowly mix the solution until a liquid product is evenly dispersed or a granular product is fully dissolved. [10]
    • Be sure to wear protective gear when diluting or applying chlorine shock treatments and any other pool chemicals.
  3. Remember to test your pool water before adding any chemicals to it. Once you’ve measured and, if necessary, diluted the right amount of chemical, add it gradually to the pool. Pour it slowly as you walk around the pool’s perimeter to ensure even distribution. [11]
    • Do not add an undiluted shock treatment directly to the water unless the product’s instructions specifically call for it.

    Tip: You’ll get more bang for your buck if you add the shock treatment at night. Ultraviolet rays break down chlorine, so the shock treatment will be less effective if you add it during the day.

  4. Some chlorine shock treatments have a pH of 10 or more, which will throw off your pool’s pH levels. If necessary, your product’s instructions will direct you to add an acidic pool water amendment to counteract the shock treatment’s high pH. [12]
    • Ask an employee at the pool supply store or consult your pool’s installer about the right combination of shock treatments and pH amendments. Use products as directed, and apply them in the order advised in the instructions.
    • It’s essential to keep the pH between 7.2 and 7.8. Ideally, try to keep it right around 7.5. If it’s too high, chlorine sanitizes less effectively. If the pH is too low, chlorine can corrode pipes, damage pool lining, and irritate skin.
  5. Shock treatments bring free available chlorine levels to 8 to 10 ppm, which is outside of the safe range for swimming. Some shock treatments work quickly, and swimming is safe after just 15 to 20 minutes. For other products, you’ll need to wait 4 to 24 hours.
    • Always test your chlorine levels after amending the pool water before you allow anyone to go swimming. Read your product’s instructions for specific wait times.
    • Bear in mind a free available chlorine level over 10 ppm may burn the test strip and yield a false reading of 0 ppm. If that happens, retest the water after a few hours. [13]
  6. At a minimum, shock your pool every 2 weeks while it's in use, regardless of how often you use it. If your pool gets a lot of use, shock it weekly. Additionally, shock it after pool parties and if it’s been contaminated, such as after a bathroom-related accident. [14]
    • The combined chlorine level, or the amount of used up chlorine, should remain under 0.2 ppm. If it exceeds 0.2 ppm, it’s time to shock your pool.
    • To maintain the pool in good shape, get a vacuum once a week. The plaster and pebbles cannot tolerate loads of dust on them. [15]
    • It does wonders to the color of the pool.
    • It is a solution under $200 because most vacuums cost less than that.
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Community Q&A

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  • Question
    Can I put the chlorine tablets into the pool and leave them there?
    Community Answer
    No. They will stain your liner. Make sure the tablets are inside some kind of floating container.
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  • Question
    Do I remove a float-type feeder before allowing anyone to swim, and how long do I wait to allow swimming?
    Community Answer
    You no need to remove the floating chlorine feeder, and you can swim whenever you want.
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  • Question
    Do I need to shock my pool while the water is clean or murky?
    Community Answer
    You should do it when the water is murky. This article goes into more detail about the process of shocking: How to Shock Your Swimming Pool.
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      Tips

      • Store pool chemicals in a cool, dry spot out of direct sunlight. Keep them out of the reach of children and pets. [16]
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      • If you’re adding chlorine for the first time, add the amount of product required to achieve a free available chlorine level of 2 to 3 ppm. The instructions will let you know how much to use to raise levels by 1 ppm per 10,000 gallons (38,000 L) of water.
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      • Application amounts and methods vary by product, chlorine form, and chlorine concentration. Always read the instructions carefully and use your product as directed. When in doubt, consult an employee at the pool supply store or your pool installer.
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      Warnings

      • Do not put your face near an open container of chlorine or any other pool chemicals. Remember to always use caution and wear protective gear when treating your pool. [17]
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      References

      1. ↑ https://www.cdc.gov/healthy-swimming/media/pdfs/Pool-Chemical-Safety-USE-poster-p.pdf
      2. ↑ https://www.cnbc.com/id/48372146
      3. ↑ https://www.acs.org/content/dam/acsorg/education/resources/highschool/chemmatters/gc-swimming-pools.pdf
      4. ↑ https://www.nitt.edu/home/students/facilitiesnservices/sportscenter/swimmingpool/SwimmingPoolMaintenance.pdf
      5. ↑ https://www.youtube.com/watch?v=nbzEaRi5Otk
      6. ↑ https://www.cdc.gov/healthy-swimming/about/home-pool-and-hot-tub-water-treatment-and-testing.html
      7. ↑ https://www.youtube.com/watch?v=nbzEaRi5Otk
      8. ↑ https://www.cnbc.com/id/48372146
      9. ↑ https://www.dummies.com/article/home-auto-hobbies/home-improvement-appliances/swimming-pools/pool-care-for-dummies-cheat-sheet-298671/
      1. ↑ https://www.nitt.edu/home/students/facilitiesnservices/sportscenter/swimmingpool/SwimmingPoolMaintenance.pdf
      2. ↑ https://www.youtube.com/watch?v=nbzEaRi5Otk
      3. ↑ https://www.cdc.gov/nceh/index.html
      4. ↑ https://www.cdc.gov/nceh/index.html
      5. ↑ https://www.youtube.com/watch?v=nbzEaRi5Otk
      6. ↑ https://www.swimmingpool.com/maintenance/vacuum-a-pool/
      7. ↑ https://www.cdc.gov/healthywater/pdf/swimming/resources/chemicalsafety/pool_chemical_storage.pdf
      8. ↑ https://www.cdc.gov/healthywater/pdf/swimming/resources/chemicalsafety/pool_chemical_storage.pdf

      About This Article

      Article Summary X

      To chlorinate a pool, first you’ll need to calculate the volume of the pool if you don’t already know it. You can estimate the volume by multiplying the length by the width by the average depth. For a circular pool, measure the diameter, divide it in half to find the radius, then use the formula πr^2h, where r is the radius and h is the average depth. Once you know the volume, test the pool water with a pool water test kit to figure out how much chlorine you need to add. The test will show multiple chlorine readings, including free available chlorine, which is active chlorine that kills germs, and combined chlorine, which is chlorine that’s already been used up. You should keep the free available chlorine level in your pool between 1 and 3 parts per million (PPM). Once you know how much chlorine your pool needs, purchase some chlorine tablets and a chlorine dispenser online or from a pool supply store. Put the tablets in the dispenser and place the dispenser in the pool according to the instructions. The tablets will continuously chlorinate the pool water as they dissolve. Replace the tablets often enough to maintain a free chlorine level of 1-3 ppm. If you’re using a chlorine product that hasn’t been stabilized, which prevents UV rays from breaking down the chlorine as quickly, you'll also need to buy cyanuric acid, dilute it, and add it to the pool according to the instructions to stabilize the chlorine. You should maintain a cyanuric acid level of about 50 ppm in the pool. In addition to routine chlorination, you’ll also need to “shock” the pool water with high levels of chlorine whenever the level of combined chlorine (used-up chlorine) becomes higher than 0.2 ppm. When the level of combined chlorine gets too high, it can cause irritation and allow algae and bacteria to grow. You should also shock the pool if you notice algae, at the beginning and end of the swimming season if you shut down your pool over winter, after heavy rain, and after pool parties to be sure it’s completely disinfected and sanitary. To shock the pool, purchase a liquid or granular chlorine shocking treatment and follow the instructions to add it to the pool water. Wait until the free available chlorine levels drop below 5 ppm before you swim in the pool again. To learn how to shock your pool with chlorine, keep reading!

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