What to Know About Cyanuric Acid

A backyard pool can be a fun and easy way to spend a summer day, but they aren’t always easy to take care of. Maintaining a backyard pool requires careful attention to the type and amount of chemicals you add to the pool regularly. 

Cyanuric acid is a pool-balancing chemical that protects the chlorine in your pool from UV rays. Without this acid, the chlorine in your pool would be broken down by the sun in just 20 minutes. Be cautious as you add it, as too much cyanuric acid can also bind to chlorine and make it ineffective. 

Curious about which products you should purchase to best balance the cyanuric acid in your pool? Let’s look at some of the products which contain cyanuric acid and what to do when the chemical balance in your pool isn’t quite right. 

What is Cyanuric Acid?

C3N3OH3 cyanuric acid CAS 108-80-5 chemical substance in white plastic laboratory packaging

Cyanuric acid is a chemical that is used in pools to stabilize the large amounts of chlorine. Cyanuric acid is a necessary ingredient in pools because, without it, the chlorine in your pool would break down when exposed to the sun within a few hours of adding it to your pool. 

Cyanuric acid works by protecting and reducing the amount of chlorine that is broken down by the sun. This means that you can rely on the chlorine in your pool to keep it sanitized for a much longer period of time. You will also save money because using cyanuric acid reduces the amount of chlorine you need to add to your pool. 

You need to be careful, however, as too much cyanuric acid in your pool can have the opposite effect as it will bind to chlorine and reduce its bacteria-fighting power. 

Does Cyanuric Acid Affect pH?

Like any chemical you add to your pool, adding cyanuric acid will affect the pH of your pool. Adding cyanuric acid lowers the overall pH of your pool while also raising the alkalinity. 

It’s important to note that cyanuric acid only raises the total alkalinity, though, and doesn’t have any effect on the carbonate alkalinity for your pool, which is the alkalinity you need to regulate for a safe pool. 

Which Pool Products Contain Cyanuric Acid?

There are several pool products that contain cyanuric acid. They are usually labeled as such or as a chlorine stabilizer. Below is a list of the pool chemicals commonly used that contain cyanuric acid. 

Occasionally, cyanuric acid may also be marketed as a chlorine protectant. If you aren’t sure whether or not a product contains cyanuric acid, check the ingredients label, as it will be printed there. 

What Happens if There’s Too Much Cyanuric Acid in Your Pool?

Like anything in life, too much of a good thing is too much of a good thing. When there is too much cyanuric acid in your pool, it won’t break down on its own. Rather, it will linger and may begin to bind with the chlorine.

When your cyanuric acid begins to bind with your chlorine, it actually reduces the ability of the chlorine to fight bacteria, making it unsanitary to go for a swim in your pool. If you check your pH levels to find they are low, then it is possible that you have too much cyanuric acid in your pool.

The only way to get rid of cyanuric acid without draining your pool and starting over is to add a cyanuric acid reducer (On Amazon). A reducer will break the binding between cyanuric acid and the chlorine in your pool to allow it to become effective once again. It will also bind with the cyanuric acid, so it won’t rebind with the chlorine. 

Cyanuric acid reducers are not cheap, and they take a while to become effective. If you have too much cyanuric acid in your pool, you will want to act immediately so you can get back to swimming as soon as possible. 

If you do not want to add a cyanuric acid reducer to your pool or don’t have the time to, the only other option is to drain your pool (at least part way) and add more water to dilute the concentration. This can be challenging and time-consuming, and it may not be entirely effective as cyanuric acid can linger in your pool filter as well as attach itself to vinyl and plaster surfaces in your pool. 

What Happens if There’s Not Enough Cyanuric Acid in Your Pool?

Screened pool attached to lanai

If there isn’t enough cyanuric acid in your pool, the chlorine in your pool will begin to break down as soon as it is exposed to the sun. In many cases, this breakdown is rapid, meaning your pool will be at unsafe chlorine levels just 20 minutes after being in the sun. 

Because cyanuric acid is so critical to pool safety, many companies have begun pre-adding it to pool chlorine. This chlorine is sold as stabilized chlorine and reduces the difficulty of balancing the chemicals in your pool considerably. 

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