Pool ownership requires a lot of upkeep – and a lot of choices. Everyone who’s spent a summer afternoon floating in a pool knows that there’s chlorine in play, but not as many people know that there are many chlorine options on the market, each with its advantages and drawbacks. Two of those options are liquid chlorine and chlorine granules.
In this article, I will compare the two types of chlorine and hopefully help you make a confident decision on which one to get. Let’s dive in.
- Both liquid and granular chlorine are highly concentrated, can keep your pool clean and sparkling, and clear your pool of any contaminants.
- Liquid chlorine is cheaper, more commonly used, is refillable, and does not leave behind any buildup.
- Granular chlorine has a longer shelf life, is easy to transport, is often stabilized (meaning it contains cyanuric acid), and generally has a lower pH value.
Two Types of Chlorine
Chlorine is a familiar product to anyone who’s been in a pool, but how does it work? When you add chlorine to a pool, its reaction to the water creates hypochlorous acid, a cleanser that kills common germs, viruses, and bacteria, from E. coli to swimmer’s ear.
Both types of chlorine have the same goal of clearing your pool of unwanted guests so you can swim in peace, so they have a lot in common.
Both liquid and granular chlorine:
- Are highly concentrated chlorine
- Are responsible for taking care of any germs, bacteria, and algae that might be in your pool
- Help keep your pool crystal clear
Outside of these similarities, you’ll find mostly the same products with a few differences under their different manufacturing processes.
These two products also have some key differences, so you’ll need to make your choice as a pool owner.
- Is more commonly used
- Is often much cheaper
- Is refillable
- Mixes easily with water
- Does not leave any buildup behind
- Have a longer shelf life, meaning you can store it
- Dissolves in water
- Easy to transport
- Are often stabilized
- Have a lower pH value
What is Liquid Chlorine?
Liquid chlorine (sodium hypochlorite) is a highly-concentrated form of chlorine made by compressing the chlorine gas with caustic soda to produce a liquid product. Liquid chlorine is even more concentrated than other kinds of chlorine because of its production.
This shock from Champion is an easy-to-use liquid chlorine perfect for getting rid of algae and cloudy pool water.
When You Should Use It
While liquid chlorine is popular with many home pool owners, it’s best for larger pools with many swimmers because of its large-quantity containers. It can also be the right choice for smaller or private pools that get a lot of use and need more regular chlorination.
Because of the way manufacturers produce liquid chlorine, it also has a couple of downsides that might outweigh its benefits for home pool owners.
Liquid chlorine has a high pH of 13, so you need to add more acid, typically cyanuric acid, to your pool to counteract the high pH and protect it from the sun.
Because of its manufacturing process, it’s also a potentially damaging product for your home pool. It can erode pool walls and tiles, so you need to be careful when chlorinating your pool with liquid chlorine. If you do use it, make sure to add it to water first to lower the pH.
What are Chlorine Granules?
Chlorine granules, also called powder chlorine or shock, are the solid form of chlorine. Manufacturers often make powder chlorine by using chlorine gas to treat lime.
These types of chlorine dissolve quickly, but you must ensure the granules dissolve entirely. Otherwise, they can leave residue or buildup on your pool walls and tiles.
Chlorine granules have a few different varieties: calcium hypochlorite, lithium hypochlorite, and dichlor.
Calcium hypochlorite is another low-cost chlorine solution, but it comes with the same issues liquid chlorine has with a pH of 12, requiring additional treatment.
In The Swim makes a very affordable cal hypo solution.
Lithium hypochlorite is another fast-dissolving, easy-to-use powder chlorine variety. It dissolves fast and leaves a pool that’s clear and free of residue, and best of all, you can swim in it right away. The bad news is lithium hypochlorite is harder to find than the other varieties.
Dichlor is sodium-based chlorine powder with a pH of 7, which can go straight into the pool without adding additional products. Its sodium base makes it an excellent choice for quick dissolving with no cloudiness or residue.
It’s also safe to use in all pool interiors, from plaster to paint, making it an excellent choice for home pools and spas of all kinds, including above ground.
Clorox makes a good dichlor-based pool shock that contains zero cyanuric acid and helps fight contaminants.
When You Should Use Them
Chlorine granules of either kind are an excellent choice for private pool owners because they don’t require as much outside product use as liquid chlorine often does.
Chlorine granules, especially dichlor, have a lower pH than liquid chlorine, so you can mix them into your pool water without having to add acid. If you’re looking for a quick, all-in-one product, chlorine granules are a great choice if a little bit more expensive.
The real downsides to chlorine granules are their price and their smaller amounts. Liquid chlorine has an advantage in being cheap and sold in bulk, while liquid chlorine, especially dichlor, is typically higher cost and sold in small containers.
Aside from these drawbacks, chlorine granules are an excellent choice for small, private pools for typical use. Just make sure to use the correct method to add granules to your pool.
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No matter what type you buy, chlorine will still help kill the bacteria, germs, and viruses in your pool and clear out algae, all while keeping your pool looking nice and clear.
You’ll need to consider whether you want to buy extra ingredients to mix with the chlorine as you’ll need to with liquid chlorine to counteract its base or if you wish to pay a little more to have a product that doesn’t have a high pH.
You should also consider the size of your pool. Are you trying to treat a small pool or spa? Powder chlorine, especially dichlor, will be an excellent choice for that. If you have a larger pool or host frequent pool parties, liquid chlorine might be a better choice for you.
Each product is great for pool owners of either kind. But they both come with their drawbacks, depending on your preferences.