Liquid Chlorine: Here’s Everything You Need To Know


In today’s post you’re going to learn everything you ever wanted to know about liquid chlorine.

Here’s what we’re going to cover:

  • Stabilized vs unstabilized chlorine
  • How to use liquid chlorine for your pool
  • How much liquid chlorine you should be using
  • And the differences between liquid chlorine and powder chlorine

Ready to dive in?

What is pool chlorine?


Chlorine is the main chemical people use in order to keep their pools disinfected, a chemical element produced by the electrolysis of saltwater that kills harmful bacteria with an available chlorine level of 12-15%.

As you probably know, it’s the chemical found in bleach and other household cleaners to clean and disinfect, and it’s also found in salt (NaCl) and is naturally present in oceans and other compounds.

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For swimming pools, it can be used in solid granular form (calcium hypochlorite) or liquid (sodium hypochlorite).

Liquid chlorine is what we will be talking about here.

Stabilized vs unstabilized chlorine

Chlorine also comes in either stabilized or unstabilized versions, each having its own use. 

Stabilized chlorine

Stabilized chlorine (liquid chlorine, chlorine tablets, granular shock) is just chlorine with cyanuric acid mixed in.

Cyanuric acid is known as a stabilizer and can even be purchased separately when needed, but a lot of the chlorine you buy already have it added. Here’s why:

UV rays will eat up your chlorine like yesterday’s lunch if you don’t have anything in the pool to protect it—this means you’re constantly having to add more chlorine, costing time and money.

The cyanuric acid acts as kind of a buffer and helps the chlorine to stay active longer.

You should always use stabilized chlorine or an added stabilizer when your pool is exposed to long hours of sunshine.

Unstabilized chlorine

So now you may be wondering why you wouldn’t just always used stabilized chlorine because unstabilized chlorine is just chlorine without cyanuric acid.

But here’s the deal—if your CYA levels get too high, that can also diminish the effectiveness of your chlorine and sometimes even lead to something called chlorine lock. 

Chlorine lock is a state where your pool’s water chemistry levels will continue to show very low chlorine levels no matter how much you add.

Unstabilized chlorine is the best choice for indoor pools or pools where there isn’t too much exposure to the sun, such as heavily shaded or covered areas.

You would also use unstabilized chlorine to give your pool a shock treatment, since you don’t want the chlorine levels to stay high for too long. 

It’s also a good product to use for a daily treatment during times of heavy use.

How to use liquid chlorine for your pool

Liquid chlorine or sodium hypochlorite is 4 to 6 times stronger than a regular gallon of household bleach and is a hazardous material, so it’s important to be careful when using it.

If it happens to come in contact with your skin, rinse off thoroughly with a hose or in the shower. Always wear protective eyewear and rubber gloves. 

Liquid chlorine is not a stabilized form of chlorine like we talked about earlier, so it should be added to your pool after dark to prevent the sun from burning it off.

The CDC recommends that your pool’s free chlorine levels be kept above 1 ppm (parts per million) when using unstabilized chlorine. If your chlorine levels rise above 3 ppm, you run the risk of eye and skin irritation for anyone in it.

But keeping it within healthy levels is simply a matter of testing your water regularly and adding chlorine only when necessary.

Once you’ve determined that chlorine needs to be added, with your pool pump running, pour the chlorine slowly into the deep end of the pool.

Leave the pump running overnight in order to keep the chlorine circulating in the pool.

Do not enter the pool until the chlorine levels are below 3 ppm!

How much liquid chlorine should you add?

First of all, check how many gallons of water your pool holds. 

Next, you’ll need to test your chlorine levels to determine how much it needs.

Most products you buy will be for about 10,000 gallons of pool water, so if your pool is larger than that, you will need more product.

Now, just follow the manufacturer’s instructions for how much to add to bring it up to your desired level. If you’re still a little confused, you can use an online chlorine calculator to help you with the math.

Liquid chlorine vs powder chlorine

I’ve taught you all I know about liquid chlorine today, but that doesn’t necessarily mean it is the best choice for your pool. That choice is up to you, so here’s the basic differences:

Liquid chlorine has a higher pH level than its powder form. It’s used primarily by commercial pool owners or pools with a lot of activity, and it’s cheaper than powder, so when it needs to be added in bulk to large pools, it makes more sense economically.

Liquid chlorine is also unstabilized, so in outdoor pools, you’ll usually have to add cyanuric acid with it to protect it from the sun and to keep it from corroding your pool. 

Powder chlorine is a little more expensive than liquid, but it has a lower pH level and you can buy it in stabilized form so that you don’t have to add much cyanuric acid, if any, with it. This makes it a little easier to use.

There are a few types of powder chlorine: di-chlor, lithium hypochlorite, and calcium hypochlorite.

They each have their own advantages, but calcium hypochlorite (cal hypo) is the most popular and most effective. 

Bottom line

It’s important to test your pH and alkalinity levels each time you test your chlorine to make sure it doesn’t lose effectiveness. 

And always be safe when handling any pool chemicals, keeping them off your skin and away from pets and people.

Now that you know everything there is to know about chlorine, you should be able to enjoy a sparkling clean pool all year.

Keeping your pool sanitized means clear, safe and enjoyable swimming!

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