What are Three Things to Know about Cyanuric Acid?

Swim season is almost over in North Georgia, but you can still swim in your pool even thwithout using a heater. 

With temperatures still in the low 80’s, there is still potential that algae may grow in a swimming pool that is not properly balanced.

When people discuss their swimming pool chemicals, they generally talk about chlorine levels and PH. You don’t hear much about the other chemicals that can affect the water clarity.  One of those chemicals is cyanuric acid (cya).  This chemical, in the words of Luke Norris, is the “sunscreen for chlorine.”

During the winter and fall, the amount of cyanuric acid in a swimming pool is not extremely important. In fact, you can let it go low and it won’t affect the chlorine levels significantly.  But, as long as the weather is still warm, this chemical needs to be monitored on a weekly/bi-weekly basis.

If you don’t monitor it, then the pool will be unbalanced and your pool will turn green. If it doesn’t turn green, the dreaded algae will show up in patches around the pool.  

In this post, we will discuss the chemical and three things to know about this chemical and how it affects your overall pool chemistry. So, what are three things to know about cyanuric acid? 

  1.  It is Non-Toxic

When discussing pool chemistry with homeowners, most are concerned about the chemicals being put in their pool.

There are only a small number of chemicals that when used you need to stay out of the pool temporarily. Cyanuric acid is not one of those chemicals. It is easy to confuse this chemical with shock because it is a granular chemical.

The granules are a larger size than the granules of chlorine shock.

But, there is a difference when you open up a new container of cyanuric acid, there is no strong odor, and you don’t need to cover your face. You also won’t get that strong chlorine smell that makes you turn your face away. 

And, if cyanuric acid gets wet in the container, there is no concern like there is with chlorine shock.  Cyanuric acid is an odorless chemical and it is called a chlorine conditioner.

Just like a conditioner applied after shampooing hair, the cyanuric acid helps to make chlorine more effective.

  1. It Can Only be Raised

The purpose of Cyanuric acid is to facilitate the job of chlorine.

When Cyanuric is at the right levels between 30-80, the chlorine can function and effectively sanitize the water.

When Cyanuric acid rises beyond the recommended range, then it takes more chlorine in the pool to kill off any algae.

So, if your cyanuric acid is above 90, then you need to have chlorine levels usually in excess of 5.0 in order to keep the pool algae free.

When cyanuric acid is above the range, then it hinders chlorine from doing its job. It is similar to other pool chemicals in that it cannot be lowered; it can only be raised. And, you only want to raise it.

Cyanuric acid in a salt water chlorinated pool

If your Cyanuric Acid is low in a salt water chlorinated pool, then you want to raise it to 80.

You don’t want to keep it at low levels because then you might have problems with algae growing in your pool.

If you want to lower cyanuric acid in a salt water chlorinated pool, then you don’t do anything.  You just continue to monitor the other chemicals and the cyanuric acid will eventually lower itself.

  1. How to Test for Cyanuric Acid

Cyanuric acid does not necessarily have to be tested every week. If you test one week and the levels in the pool are in an acceptable range, then you don’t have to do anything.

Also, if the chlorine is in range, then you can assume that the cyanuric acid is also in range.

Cyanuric acid is different in a chlorine tab pool and a saltwater chlorinated pool.  In a saltwater chlorinated pool, the levels of cyanuric acid will usually be at an acceptable range.

But, in a chlorine tablet pool, the cyanuric acid is going to be at a higher level than is recommended.  This is because the chlorine tabs have cyanuric acid in their makeup.

The more chlorine tablets that are added to a pool, the more that cyanuric acid will rise. And, the only way that you can lower the cyanuric acid is to drain all the water out of the pool.

If you found this helpful,  please make sure to comment below.

Thank you.

Marti Norris


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