How To Add Cyanuric Acid To Pool

How To Add Cyanuric Acid (Stabiliser) To Pool - Full Guide

Pool stabiliser, chemically known as cyanuric acid or CYA, is an essential component in outdoor swimming pools that protects free chlorine molecules in your water from degrading from sunlight.

While many types of chlorine are stabilised already, using unstabilised chlorine (which I recommend) means you have to add stabilizer separately. But how do you add stabilizer to your pool?

In this article, we will review the supplies you will need, as well as how to actually add cyanuric acid to your pool.

Gather Supplies

Before learning how to add cyanuric acid to your pool, you will need to gather some essential equipment. This includes your cyanuric acid product, a stabiliser testing kit, and a mixing bucket if one is required for your product.

CYA is available in powdered or liquid forms, and some powdered forms require mixing. Our favourite choice for adding cyanuric acid to your pool is this pool stabiliser.

Even though it is powdered, this formula does not require mixing and can be added directly to your pool’s skimmer box while the filter is running.

How To Add Stabiliser To Your Pool

Step 1 - Test Cyanuric Acid Levels

To begin, use a CYA testing kit to identify the current levels of stabiliser that are present in your pool. In most cases, ideal levels of stabiliser range from 30-50 parts per million (ppm). If your cyanuric acid levels are low (30ppm or lower), you will need to add stabiliser to your pool.

Step 2 - Calculate How Much Stabiliser To Add

When calculating how much CYA you will need to add to your pool, it is important to follow your product manufacturer’s dosage guidelines due to varying strengths of products.

To increase your cyanuric acid levels properly, you will need to know the volume of your pool and your target level of CYA.

For a pool that is 50,000 litres in volume, 1,250 grams of stabiliser will create an increase in cyanuric acid levels of 25ppm. If you are unsure about how much product to use, it is better to use too little product first and add more later if necessary.

Excess cyanuric acid can actually reduce the effectiveness of your chlorine, so it’s critical that you stay within the recommended 30-50 ppm range.

You can also use our pool stabiliser calculator to help you work out the right dose for your pool.

Step 3 - Prepare To Add The Product

Before adding CYA to your pool, you should balance the other aspects of your pool’s chemistry.

First, you should adjust your pool’s free chlorine levels to between 2-4ppm. Then, you should make any necessary changes to your pool’s pH and total alkalinity, so that these levels fall between 7.2-7.6 and 80-120ppm respectively.

As you prepare to add your product, we recommend using additional safety equipment such as gloves and protective glasses or goggles. If required for your choice of product, follow any mixing instructions, and then distribute the solution into your pool as recommended.

Step 4 - Wait For Your Chemistry To Adjust

After adding new amounts of cyanuric acid to your pool, it can take time for your CYA levels to adjust.

This can take anywhere from 6-12 hours depending on your choice of product, and the ideal wait time for you should be indicated by guidelines provided by your product label.

Typically, your pump and filter should be left running during this waiting period to ensure adequate mixing.

Step 5 - Retest Your Cyanuric Acid Levels

Once you have observed the recommended waiting period for your choice of stabiliser product, you will need to retest your cyanuric acid levels. Upon retesting, your pool should ideally now be reading within the appropriate range of 30-50ppm.


Pool stabiliser is an essential component of water chemistry in outdoor pools that increases the longevity of your chlorine.

Without enough cyanuric acid in your pool, your chlorine will degrade very quickly, requiring you to use more and more of it in order to keep your levels adequate. Luckily, cyanuric acid is fairly easy to add to your pool.

Do you have any questions about how to add cyanuric acid to your pool? Get in touch, we’d love to help!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.