Pool Stabilizer: The Ultimate Guide to Pool Water Balance

Most swimming pool owners know the importance of pool water balance and how to test for pH and chlorine. They understand how to maintain these measures of pool health at the proper levels. But there is one aspect of pool water balance a lot of pool owners struggle with.

In your pool ownership journey, you would have heard of pool stabilizers, pool conditioners, chlorine stabilizer or Cyanuric acid (CYA). These terms are often used interchangeably and always in reference to the chlorine levels of a pool.

But what is Cyanuric acid (CYA) or a pool stabilizer? What does it do and why do you need it?

What is a pool stabilizer?

Outdoor swimming pools are constantly exposed to the harsh effects of sunlight. One of the areas where this effect is most visible is in the pool’s chlorine levels. Chlorine, a useful chemical for maintaining pool sanitation, is unfortunately very sensitive to UV rays. Under direct sunlight, swimming pool chlorine quickly dissipates and pools can become unusable very quickly.

To keep this from happening, pool owners need some means to protect the chlorine in their swimming pools. This is what a pool stabilizer does. It acts as a buffer inside the water to shield pool chlorine and prevent it from being dispersed by the sun’s UV rays. Without a stabilizer, the sun can burn up to 90% of the chlorine in an outdoor pool within a few hours.

Although CYA inhibits the degradation of chlorine in a swimming pool, it does not interfere with its disinfecting properties. Chlorine is still able to perform its normal function because the stabilizer combines with it to make chlorimide, which is also capable of sanitizing the water. Without CYA, the pool would use twice the amount of chlorine it should.

The only pools that don’t need CYA are indoor pools and jacuzzis that use bromine.

Why stabilizers need to be balanced

But in spite of how important a pool stabilizer is, having the wrong amount in the pool can itself be a problem. As RentSmartUSA warns, you can either have too much or too little stabilizer in your swimming pool. And both will have adverse effects on the pool.

When stabilizer levels in a pool are too high, it overpowers the chlorine and makes it ineffective. This is because the Total Dissolved Solids (TDS) in the pool escalates to the point where it impairs chlorine’s ability to kill bacteria and algae.

Too much CYA can also lead to a condition called "purple" or copper cyanurate. And it will cause chlorine block. This is a situation where chlorine tests read negative even when there is chlorine in the water.

Too little CYA, on the other hand, will leave the pool’s chlorine unprotected and in a few hours, it will be depleted by the sun. This leaves the pool exposed to bacteria and algae. Excessively low levels of CYA mostly happen when there has been heavy rainfall or after a large pool party where the pool water level was significantly lowered. Pool stabilizer levels don’t easily drop because CYA is not easily depleted.

How much stabilizer does your pool need?

When it comes to stabilizer, it’s important not to have too much or too little. If there is CYA in a pool, it probably doesn’t need more. This is because the only ways CYA leaves the water is through draining and diluting with hose water, splash out, or backwashing. Adding a stabilizer to a pool that doesn’t need it is a waste of money and it could worsen the very problem that stabilizers are meant to solve; improve the function of chlorine.

If tests reveal that a pool actually needs stabilizing, what is the right quantity to add?

The standard rule is a lower limit of 30 parts per million (ppm) and an upper limit of 60 ppm. If the pool is located in a very sunny region, the lower limit may be raised to 40 ppm

Some would recommend an upper limit of 80 ppm for warmer areas and it should be noted that pool stabilizer levels above 50 ppm will cause chlorine lock.

How should you add the stabilizer to your pool?

There are "stabilized" chlorine products such as di-clor and chlorine tablets that already contain CYA and make it unnecessary to add pool stabilizer separately. These regularly add stabilizer to the water throughout the year. However, if you need to add the stabilizer separately, here are the steps: With the pump running and the skimmer line open, remove the skimmer basket and slowly pour your stabilizer granular in through the skimmer. It’s important to have a clean filter while doing this and not to backwash or clean your filter a few day after as these granules usually take 1 to 2.5 days to dissolve depending on the water temperature. If you are pouring stabilizer through the skimmer it’s also important to pour it in slowly as pouring too fast can clog your pump’s basket and obstruct water flow. Another method of adding stabilizer to your pool is simply pouring it around the edges of your pool. This is especially convenient if you have an automatic cleaner that will pick up the granular from the bottom. The reason some might advise against this method is because the CYA granular is slow dissolving, it might sit on the bottom of your pool for 1-3 days. This is really nothing to worry about as it will not stain or damage your surface. There you have it, what you need to know about pool stabilizers. Now if you think you need any or any other pool chemicals or supplies, feel free to check out our online store for everything you need to keep your pool clean, safe and beautiful!