Pool Stabilizer! Everything You Need to Know About It


Chlorine is pretty unstable on its own and easily breaks down in the presence of UV radiation. In direct sunlight, you will lose more than half of the chlorine you just added to the pool in an hour.

Pool Stabilizer binds free unstable molecules of chlorine and makes it stable, prolonging its lifespan by up to five times.

This article is all about your pool’s friend, a Pool stabilizer. How it works, why you need it, and everything else you should know as a pool owner!

What is Pool Stabilizer

In the pool industry, there are many names for it, pool conditioner, pool stabilizer, chlorine stabilizer, or just simply its chemical name cyanuric acid, aka CYA.

You can get it in its pure form as powder, or it comes in combination with chlorine, generally referred to as stabilized chlorine.

Stabilized chlorine can be purchased as tablets (trichlor) or granules (dichlor) and can be used for regular chlorine supply to the pool.

If you are using the stabilized chlorine products, you don’t need to add the stabilizer separately.

In fact, due to the overuse of stabilized chlorine, the levels of CYA can creep up very fast. As you need a constant supply of chlorine, you need to add it regularly, but the stabilizer does not break down and stays in the pool.

This condition, when the levels of stabilizer go beyond the recommended highest levels of 50 ppm, is termed “creep.”

Higher than normal levels of CYA is not good news for your pool as they reduce the efficiency of chlorine. This can lead to many problems, like bacteria and algae growth.

You need to keep a tab on the pool conditioner levels by regular testing.

Make sure that you are testing these levels at least once a week.

Related: How to lower stabilizer levels in pool water!

What Kind of Pools Need Stabilizer

As a pool stabilizer protects chlorine from sunlight, it is essential only for pools that get direct sunlight.

You won’t require it for indoor pools or pools with significantly less or no sunlight. If you use CYA for such pools, its levels will go up over time as it does not break down on its own.

For this reason, stabilized tablets or chlorine is not recommended for indoor pools. Only use chlorine without CYA in indoor pools.

However, some indoor pools that get UV light exposure will require low doses of stabilizer.

Saltwater pools are also basically chlorine pools where the final sanitizer is chlorine only, so they also need stabilizer if they are outdoor.

So, you don’t have to worry about using a stabilizer if you have an indoor pool. Just use unstabilized chlorine for regular sanitization.

How Pool Stabilizer Works

So by now, we know that as soon as you add chlorine to an outdoor pool, the sun starts working on it immediately.

You can lose almost all the chlorine in the day itself when you add it.

That’s no good for your pool and pocket. You need to add more chlorine to keep up with the chlorine demand, and this chemical is not cheap.

The best option for you is to pair chlorine with a stabilizer. A stabilizer or cyanuric acid makes a strong bond with chlorine ions and stabilizes them.

In stabilized form, chlorine molecules are more stable than when they are alone. Sunlight takes more time to break them, and they can last up to 5 times longer.

In short, if you are using a stabilizer in your outdoor pool, you need to put in chlorine every 3 to 5 days rather than daily. That is a huge effort and money saver.

So, if you can maintain a level of stabilizer between 30 to 50 ppm, your pool will need less chlorine and remain sparkling clean.

Related: Ideal chlorine levels for your pool!

Why 30 to 50 ppm Levels are Important

Maintaining the right amount of cyanuric acid is important as too less, or too much of it, can leave your chlorine ineffective.

The ideal levels of CYA in your pool are 30 to 50 ppm. In recent times experts believe that, in fact, more than the amount of CYA, it is the ratio of CYA to chlorine that is more important.

Free chlorine available in pool water should be around 7.5% of CYA.

Here is the table for reference to maintaining chlorine levels in your pool according to CYA levels.

CYA LevelsCl Need
10 ppm0.75 ppm
20 ppm1.50 ppm
30 ppm2.25 ppm
40 ppm3.00 ppm
50 ppm3.75 ppm

The Downside of Pool Stabilizer

Stabilizer binds with the chlorine and reduces its oxidation-reduction potential or, in simple terms, its ability to kill bacteria and algae.

At any time when a stabilizer is present, the majority of chlorine molecules are bound to it, and only some part is free to fight germs. So, a stabilizer increases the life span of chlorine but decreases its killing potential.

The best part is your pool does not need the 3 ppm of chlorine to kill unwanted guests. Algae that is tougher to kill than bacteria needs 0.05 ppm chlorine to be eliminated.

At 30 ppm of CYA, only 3% of chlorine is available to clean our pool. That means out of the recommended 2.25 ppm, 0.07 ppm is available, which is enough, and is more than 0.05 ppm of chlorine, to get the job done.

The problem arises if the CYA levels go up from 50 ppm.

At 60 ppm CYA, less than 2% chlorine is available for sanitization, and the rest is bound to CYA.

This can lead to a condition called chlorine lock where not enough chlorine is available to do the job, no matter how much your add to the pool.

It can lead to the growth of algae and bacteria, which may be harmful to swimmers’ health. So you need to lower pool stabilizer levels if they are above 50ppm.

How Much Pool Stabilizer to Add

There are many variations in recommendations starting from 10 ppm to 100 ppm. 100 ppm is the maximum amount allowed by WHO.

Salt pools have recommended amount of 50 to 60 ppm. But for the normal chlorine outdoor pool, we recommend strictly maintaining the stabilizer levels between 30 to 50 ppm.

As we discussed above, the ratio between chlorine and CYA is most important, and you need CYA between these levels so that recommended 1 to 3 ppm chlorine range can work effectively.

First of all, you need to calculate the amount of water in your pool. Fill in the details here according to your pool shape.

Water Volume Calculator

Select your pool type

Here is the table on how much stabilizer to add to increase its levels.

Raise by5,000 gal10,000 gal20,000 gal
10 ppm6.5 oz13 oz26 oz
20 ppm13 oz26 oz52 oz
30 ppm19.5 oz39 oz78 oz
40 ppm26 oz52 oz104 oz

Note: Exception to the 30 to 50 ppm rule is applied only when you have encountered a crypto problem in your pool. Not the Bitcoin one, but the nasty bacteria cryptosporidium that can get in your pool in case of contaminated defaecation.

These bacteria cause the disease cryptosporidiosis, where patients may suffer watery diarrhea, vomiting, and nausea, among others.

This bacteria is resistant to normal chlorine levels and need super chlorination. Superchlorination will also only work when the levels of stabilizer is below 15 ppm.

You may also need to backwash or replace the filters to completely get rid of this bacteria.

When to Add Pool Stabilizer

Unlike other chemicals you are dumping in your pool every other day, and your pool demands more, a stabilizer is pretty stable and stays in your pool for a long.

It stabilizes chlorine, but it is also very stable by itself, and it does not break down on its own. Even if water evaporates in your pool, the stabilizer will stay in the remaining water in a more concentrated form.

Therefore, you need to add a stabilizer to the pool only once a year or when you are refilling the pool with fresh water, which may reduce the pool conditioner levels.

Also, when it rains, there is a chance that your pool water will get diluted, and you need to add more stabilizer.

Obviously, before adding a stabilizer anytime, always do the testing.

If you are using stabilized chlorine, the levels of the stabilizer may creep up due to its longevity.

Hence more testing! Testing and testing more regularly is the key to keeping your pool chemistry intact.

Related: How to increase pool stabilizer levels!

How to Add Pool Stabilizer

You can add a stabilizer to the pool by using the stabilized chlorine. But, if you want to raise cyanuric acid to a specific level, then adding the pure form of CYA is the best option.

You can easily find this chemical at pool stores or online as a pool conditioner or stabilizer.

You can calculate how much chemical your pool needs to reach between 30 to 50 ppm levels, as discussed above.

Note: Don’t add all the chemicals you calculated in one go. Add half first, circulate water for a few hours and test CYA levels before adding more. Also, don’t add directly to the pool or filter as it can damage your equipment.

How to do it:

  1. Pool stabilizer is an acid, so wear protective gear like goggles and gloves before handling it.
  2. Add the measured amount to a bucket of half or a quarter of warm water and mix the chemicals properly.
  3. Add water first to the bucket and not chemicals, as that may cause fumes and splashes.
  4. Add the mix to the skimmer and let water circulate for a few hours.
  5. Test the water again and add more if required.

When Not to Use Pool Stabilizer

A pool stabilizer is entirely unnecessary for indoor pools that do not get any sunlight. It may reduce the chlorine effectiveness in indoor pools without providing any apparent benefits.

Other than that, in hot bathtubs, you don’t need to use a pool stabilizer. A type of pseudomonas bacteria that is typically resistant to stabilized chlorine can cause folliculitis in people using tubs.

Hence, it is recommended to use only unstabilized chlorine in bathtubs.

In addition, as we discussed above, during chlorine lock or crypto contamination, you should not use a pool stabilizer.

Related: How to reduce pool stabilizer levels!

Is There an Alternative to Pool Stabilizer

A pool stabilizer is a must for outdoor chlorine pools. So, if you are planning to keep an outdoor chlorine pool, then the answer is NO.

In that case, there is no alternative to a stabilizer for your pool.

There are other alternatives to chlorine pools, like bromine pools, but bromine is also sensitive to sunlight, and on top of that, it also does not have any stabilizer.

But there is an alternative if you can sanitize your pool with an oxygen generator rather than chlorine, then you don’t need a stabilizer.

An oxygen generator kills bacteria by oxidizing it and doesn’t need chlorine; hence no stabilizer.

Stabilize Your Chlorine For It to Work Longer

Chlorine is what helps keep your pool clean from bacteria, algae, and organic contaminations. But your chlorine will work only when it can save itself from UV rays.

Protect your chlorine with the help of a stabilizer and help it do its job and do it for longer. Adding a stabilizer once a year to your pool will save you from the effort of adding chlorine every day.

Plus, huge money savings.

So, in an outdoor pool with direct sunlight, using a stabilizer is a must. Just keep an eye on its levels so that they don’t creep up from 50 ppm.

But you don’t need to use it in the case of indoor pools and hot bathtubs.

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