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Chlorine, by any other name, is NOT the same



Chlorine, by any other name, is NOT the same
By Jenelle Lockard

Chlorine, for something so many people know about, it’s amazing how little most people really know about it. Did you know there are 5 types of Chlorine? How about that there are different percentages of Chlorine? Or how about if you smell Chlorine you need more Chlorine? Answer no to any or all of these questions? If so don’t worry, you’re not alone. Let me give you a quick lesson in Chlorine 101.

Myth #1: “Chlorine is Chlorine, it’s all the same.”
There are 5 types of Chlorine; Sodium hypochlorite, Lithium hypochlorite, Calcium hypochlorite, Dichlor, and Trichlor. The first difference is Sodium, Lithium, and Calcium are un-stabilized Chlorine. Dichlor and Trichlor are stabilized. Stabilized chlorines have Cyanuric Acid which acts as a type of sunblock for the Chlorine. The sun will break down Chlorine causing it to burn off quicker; Cyanuric Acid slows this process down. Therefore, Dichlor and Trichlor are used in outdoor pools as pucks/tablets. Because indoor pools do not need to worry about the sun, and do not need Cyanuric Acid, they usually use the other 3.

Myth #2: “Doesn’t Chlorine all work the same. What’s the difference if I get it from my local mart store or from a pool store? I can just use bleach if needed. ”
There is a big difference. Yes, for the most part, all Chlorine is a disinfectant/sanitizer, but each of the 5 types has different compounds, qualities, and uses.

  • Sodium Hypochlorite

Sodium Hypochlorite is a liquid Chlorine and has around 10-12% available Chlorine. Available Chlorine (AC) is the amount of Chlorine released in the water to disinfect. Bleach, which contains Sodium Hypo, only has 5% AC which is why bleach is not a good pool disinfectant. Because of its liquid nature Sodium Hypo is usually applied to a pool through an automatic chemical feeder. Big water parks and large commercial pools are the common users of Sodium Hypochlorite.
Side note: Salt pools are still Chlorine pool because the salt cell breaks the salt down into Sodium Hypochlorite.

  • Lithium Hypochlorite

Lithium Hypochlorite is granular Chlorine with a 35% AC. Lithium dissolves very quickly making it great for super chlorinating (shocking) vinyl lined and fiberglass pools and those who have problems with hard water and Calcium levels. But its low active strength and high cost make it home pool disinfectant rather than commercial pool disinfectant.

  • Calcium Hypochlorite

Calcium Hypochlorite is commonly seen as granular Chlorine but also is in puck/tablet form. Calcium Hypo has an AC of 40-78% and it the most popular of the Chlorines. Calcium Hypo is used not only to shock a pool but is used in erosion feeders as the main way to disinfect a pool. Calcium Hypo is used regularly in both home and commercial pools and is usually what is seen on your local mart shelves.
The difference between the Calcium Hypochlorite sold in pool stores versus local mart stores is the AC level. Remember: the higher the AC level the more disinfectant is going into your pool. The cost may be lower but so it the amount of chemical you’re getting.

  • Trichlor and Dichlor

As stated above, both are stabilized Chlorines making them perfect for outdoor pools and are usually seen as pucks/tablets/sticks though granular forms are available. Their AC level is usually around 80-90% and introduced to the water thru chemical feeders or skimmers. Because of their high AC level the granular form it commonly used to treat pool problems due to algae or a Chlorine demand.

Myth #3: “I smell Chlorine, there is too much in the pool.”
Now to get a little scientific, Hypochlorous Acid is the disinfectant form of Chlorine in the water known to most as Free Chlroine, or what you test your water to see what level it is. Hypochlorous Acid is made up of a Hydogren ion and a Hypochlorite ion. These two Ions join and separate a number of times in the water. Their main purpose is to break apart, attack the bad stuff, regenerate, and reconnect keeping the water disinfected.

When you smell a “Chlorine” smell it’s the Hypochorous Acid that broke apart, attacked the bad stuff, but has nothing to regenerate and attach itself to. This give off the smell which makes one think the level is too high when it’s actually too low. The best remedy is to shock the pool to raise the Chlorine level and to get rid of the bad stuff.

Hopefully I cleared up some of the common questions and myths about Chlorine. I also hope this information helps aid you in your decision making process in what Chlorine is right for your pool. Remember, not all Chlorine is the same and cheaper isn’t always better.

josh the otter

pool safely

jabari of the water

About Jenelle Lockard

Jenelle Lockard is an adjunct faculty swimming instructor for Penn State- Altoona and a do sales for Greenwood Pools. She is a Lifeguard/Cpr/First Aid Instructor, Pesticides Applicator in PA, and a Certified Pool Operator. She enjoys teaching swimming lessons, water aerobics, and work with local companies and pools in water safety and compliance issues.

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