What is Swimming Pool Stabilizer & When To Add It

Stabilizers are a major part of getting your pool chemistry just right. And if you’re anything like I was, you’re probably at a loss as to what stabilizer does and how much you need. These are questions many pool owners struggle to answer. 

But don’t worry, you’ve come to the right place. 

In this article, we’ll discuss what stabilizers do, when to add them, and how to maintain them. 

Let’s jump in.

swimming pool water stabilizer
Swimming Pool Water Stabilizer

What is Swimming Pool Stabilizer & When To Add It?

A swimming pool stabilizer is a chemical that helps protect your chlorine chlorine so it can effectively sanitize your pool. It does this by stabilizing the chlorine molecule that would otherwise breakdown in direct sunlight.

You should only add stabilizer if your levels are below 30ppm. Usually, all you have to do is check the level of stabilizer (cyanuric acid) in your pool every week to judge whether it’s doing the job or not.

There’s a lot more to stabilizers than just this though. You’ll want to make sure you’re adding it at the right time, the right amount to add and most importantly, when you shouldn’t add stabilizer. 

Read on to find out more about how to manage pool stabilizer. 

What is Pool Stabilizer? 

Pool stabilizer is a chemical that is used in chlorinated swimming pools to prevent chlorine from breaking up in direct sunlight. When exposed to UV light, free chlorine loses its ability to sanitize the water.  

Composed of cyanuric acid, stabilizers stick to the chlorine molecule, keep it from dissipating in the sun, and enable chlorine to fight off bacteria and other pathogens in the water.  

You can purchase stabilizers in the form of granules or liquid. Some people also prefer to buy stabilized chlorine. Stabilized chlorine is free chlorine that already has a stabilizer mixed with it. 

It is often a practical option to use stabilized chlorine as you only need to worry about adding one chemical to your pool instead of two. That said, it does limit your ability to control the level of stabilizer in the water and can potentially cause you to have high stabilizer levels.

How to Use Pool Stabilizer?

When preparing to add pool stabilizer, you need a good safety kit. Get some safety goggles and acid-resistant gloves ready before handling the product. 

The first thing you’ll need to do is test the water. Never add anything to your pool before testing the water. Once you’ve done that, you can judge how much you need to raise or lower the level of stabilizer. 

To do this, I recommend you read the instructions on the packaging as each product will differ in the strength of the stabilizer.

Keep in mind that you’ll have to calculate the volume of water in your swimming pool before you can judge how much stabilizer is needed.

Usually, you’ll be asked to mix the product with warm water in a bucket before sprinkling it on the edges of your pool or in the skimmer box. However, that depends on whether you buy stabilizer in granulated or liquid form. 

Again, make sure you read the instructions before using the product. But maybe you’re wondering when would be a good time to add stabilizer to your pool? We’ll discuss that in the next section.

When to Add Pool Stabilizer?

The level of stabilizer in your pool should be between 30ppm and 50ppm. This means that you should add stabilizer as soon as it drops below 30ppm. 

If stabilizer levels are below 30ppm, then you should add some to your pool. The water in your pool will probably look a bit green and dirty. This is because there isn’t enough stabilizer to keep the free chlorine from breaking up. And if this happens, the lack of chlorine will allow algae and bacteria to grow.

As a pool owner, you should always have a test kit at your disposal. This way, you can test the water every week to make sure the chemicals in the water are balanced. 

So make sure you have a few test strips available to you, and keep an eye on whether it tests for stabilizers (which is often called cyanuric acid or CYA for short). 

With that in mind, you should know that unlike other chemicals, stabilizer doesn’t evaporate, which means that too much stabilizer in your pool will have to be removed manually by partially draining your pool. 

Stabilizer can often be slow to dissolve. We’ll discuss some tricks to remedy that problem later. But for now, it’s just useful to know that you should get your pump running for several hours (preferably overnight) before testing the level of stabilizer in your swimming pool.

Often, stabilizer will sink to the bottom of the pool, stick to the walls or cluster around the filter. And since the stabilizer hasn’t dissolved yet, the test strips won’t give you an accurate reading. 

If your stabilizer level is over 50ppm, it will overwhelm the free chlorine and make it ineffective against bacteria – chlorine isn’t effective with high levels of stabilizer. The result is very much the same. Greenish, dirty water and/or a cloudy appearance. 

Doesn’t Chlorine Contain Stabilizer?

Pure chlorine doesn’t contain stabilizer. This means that if you add chlorine to your outdoor pool on its own, more than half will dissipate within a few hours. This is often called unstabilized chlorine. 

You can find unstabilized chlorine in 3 different forms: 

Lithium hypochlorite and calcium hypochlorite both come in a granulated form. This makes it easy to dissolve in water and tends to have a higher concentration of chlorine. 

Sodium hypochlorite is a liquid form of chlorine that you usually pour on the edges of your pool.

That said, you can buy chlorine products that have been mixed with stabilizers. These are called stabilized chlorine. Stabilized chlorine can be helpful as your pool will stay clean and UV lights shouldn’t break the chlorine molecule apart anywhere near as quickly. 

However, it’s a disadvantage when you need to lower the level of stabilizer. 

You can find two forms of stabilized chlorine. Trichlor, which takes longer to dilute in water thus sanitizes it for longer. And sodium dichlor, which is known for killing black algae and for its neutral Ph levels. 

You can read all about stabilized chlorine in our article Should You Use Dichlor or Trichlor for Your Pool?

Whether you pick stabilized or unstabilized chlorine is a matter of personal preference. Depending on the type of pool you own, you might find one more useful than the other. 

Here’s two stabilized chlorine products we recommend:
> Rx Clear Dichlor Chlorine

> Stabilized Chlorine Tablets (Trichlor)

How to Test Pool Stabilizer Levels?

To test pool stabilizer levels, buy some test strips or a quality liquid test kit and apply them to the water once a week. Usually, you can dip a test strip in the water, wait for it to react to the chemicals in your pool, and check if the colors match the color chart on the box.

As usual, read the instructions on the packaging and follow them carefully. And remember to check whether this particular test kit tests for cyanuric acid.

We recommend this liquid test kit:

Taylor Technologies Test Kit
Taylor Technologies Test Kit

How to Raise Pool Stabilizer Levels?

While stabilizers don’t evaporate as other chemicals do, a lot of splashing, rain, and water evaporating during a hot day can influence the level of stabilizer in your pool. 

Again, this is why it’s so important to test the water each week. If you find that your levels are below 30ppm, then you need to add stabilizer. Luckily, this is quite an easy issue to solve. 

To do this, follow the 4 easy steps below:

Step 1: Test the water. 

Step 2: Calculate the volume of water in your pool.

Step 3: Calculate by how much you need to raise the level of stabilizer.

Step 4: Add stabilizer after reading the instructions.

For more information on how to add stabilizer to your pool, here’s a more in-depth article you can read now.

How to Properly Dissolve Pool Stabilizer?

Because stabilizer is a lot denser than water, it takes time to dissolve in your pool. Luckily, there are a few tricks you can use to remedy this. 

One of these tricks is to mix it with warm water before adding it to your skimmer box. To do this, make sure you’ve got protection like gloves and goggles. 

Take a large bucket, add warm water, add the stabilizer to the water, and stir gently before adding it to the skimmer box.

Another good way of helping stabilizer dissolve is by using a sock. 

To do this, take the amount of stabilizer you need, put it in a pool skimmer sock and place it in the skimmer box. Once you’ve done this, put your pump on a “filter” or “circulate” setting for 48 hours. 

Keep in mind that it can take anywhere between two to five days for stabilizers to dissolve properly, whatever method you choose to implement. 

So make sure you leave it long enough before testing the water. Again, you can take a look at the instructions to get an idea of how long you need to wait.

How to Lower Pool Stabilizer Levels?

If the water in your pool is turning green, then you might need to lower the level of stabilizer. This often happens when stabilizer levels go over the 50ppm mark. 

As I’ve said above, this is a common, but irritating issue for pool owners since stabilizers will continue to build up unless you do something about it. 

Luckily, there is a simple solution to this problem. Here are 4 simple steps you can follow: 

1. Stop using stabilized chlorine.

2. Drain some of the pool water.

3. Top it up with fresh water.

4. Get the pump running for a few hours to encourage water flow.

5. Test the water again and repeat if the levels of stabilizer are still too high.

When lowering the level of stabilizer in your pool, make sure you give the filter a rinse or change it altogether as there might be some undissolved stabilizer left in there.

For more information on how to lower pool stabilizer levels, here’s a more in-depth article you can read now.

What happens if you have too much stabilizer in your pool?

When the level of stabilizer in your pool exceeds 50ppm, the free chlorine is inhibited by the stabilizer. This is also referred to as a chlorine lock, or over stabilized water.

As a result, your water will attract bacteria and either become cloudy or begin to look like a pond. 

If this happens, make sure you dilute the water in your pool until the levels are between 30ppm and 50ppm (see step-by-step instructions above). 

And check whether you’re using stabilized or unstabilized chlorine. Stabilized chlorine will make it difficult for you to lower the level of stabilizer in your pool. Stop using them until you get your stabilizer levels under control. 

Pool Stabilizer Alternatives

Because it takes so much effort to get your pool chemistry just right, it’s understandable that you might be wondering whether there are other alternatives to stabilizers. 

The simplest answer I can give you is yes, there are alternatives to stabilizers if you choose to sanitize your pool with something other than chlorine. If that isn’t an option for you, then the answer is no.

Because stabilizer binds to free chlorine molecules specifically, other sanitizers either don’t require stabilizers at all or aren’t usable in outdoor pools. 

Bromine is a good example because it breaks up in sunlight. But there is no effective stabilizer for bromine, which is why it’s only used in indoor pools.

That said, there are other good alternatives to chlorine that do not dissipate in direct sunlight. 

An oxygen generator, for instance, oxidizes bacteria. This sanitizes your pool without the need for stabilizers.

Some people think saltwater pools are an alternative to stabilizer. This isn’t correct though, saltwater pools do require stabilizer – more than chlorinated pools. 

Test Kits for Pool Stabilizer

When purchasing a test kit, make sure it tests for cyanuric acid as this is what stabilizers are made of.

The most accurate test kits are liquid or drop test kits. Test strips work too and are a more convenient solution but not as accurate as liquid test kits. You’ll also want to make sure multiple test strips are available so that you can go through the process multiple times. 

Recommended Products:

Final Thoughts

Here is a quick summary of what we’ve discussed in this article:

  • Stabilizers keep the chlorine molecule from breaking up so that it can fight off bacteria in outdoor pools.
  • Add stabilizer the moment it drops below 30ppm.
  • The level of stabilizer should sit between 30ppm and 50ppm.
  • Stabilizers can take several days to dissolve
  • Stabilizers don’t evaporate like other chemicals, so make sure you allow enough time before adding more.
  • You should check your level of stabilizer once a week. 

Now that you’ve found the perfect balance, make the most out of that lovely crystal clear water! What do you do to keep your swimming pool stabilized? Let us know in the comments.