Cyanuric Acid Vs Muriatic Acid – DIFFERENCES & SIMILARITIES

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Muriatic Acid lowers pH, Cyanuric Acid protects the chlorine from the sun and buffers the chlorine. Yes, they are both acids but they serve different purposes for the pool owner.

Cyanuric Acid Vs Muriatic Acid

Cyanuric acid features a chemical formula CNOH, whereas muriatic acid is a diluted form of hydrochloric acid, HCI.


Cyanuric acid for swimming pools (or CYA for short) is used for protecting chlorine or stabilizing it from degradation by the Sun’s UV rays.


Muriatic acid is the one used for various purposes including reducing alkalinity and pH cleaning stains and cleaning filters.

The two are definitely not interchangeable and you cannot substitute CYA for muriatic acid or vice versa.

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What is the Purpose of Muriatic Acid in Swimming Pools?

Pool owners use MYA to reduce pH levels. So, if your Ph level is high, then you need this added to your swimming pool according to instructions. Additionally, it will reduce alkalinity and pH level in the water.

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Although they do a similar job, pH Decreasers (known as Sodium Bisulphate) sold by stores are not the same as MYA, but they perform a similar role.

Alkalinity and pH are one of the factors you need to monitor when it comes to your pool. If this isn’t correct, the water can irritate and sting skin and eyes and you also risk your pool being more susceptible to waterborne diseases – chlorine needs the correct pH level (7.2 – 7.6) to work effectively.

Muriatic Acid is stronger than Sodium Bisulphate and will reduce the pH levels and alkalinity quicker. It’s just added to the pool to bring down the pH levels.

Dilute this acid before you add to your pool. To do this, use fresh tap water and not pool water. Acids typically have dangerous reactions if you don’t do this.

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MYA can also clean rust stains off pools and its environment, cleaning grout and also for cleaning pool filters. Yeah, it’s that powerful a cleaner.

Note: don’t use it for cleaning vinyl pools or pools with liners. It is too strong for this purpose.

Cyanuric Acid Vs Muriatic Acid

What is the Purpose of Cyanuric Acid in Swimming Pools?

Cyanuric Acid granules are also referred to as pool sunscreen or stabilizer.

Chlorine is the most popular sanitizer for swimming pools. It also helps to keep harmful bacteria and algae in the water.

Note: Chlorine loses its effectiveness when exposed to UV light, and it degrades fast. In fact, after only a few hours, chlorine can lose half its effectiveness, meaning all that expensive chlorine you just added to your pool has been wasted.

Enter chlorine stabilizer or Cyanuric acid (CYA). CYA can be used to protect and preserve the active chlorine. It comes premixed with CYA or added to pool water.

The CYA works by forming a bond with the chlorine. Once this bond is formed, UV light no longer affects chlorine. Now your chlorine can work effectively and will last exponentially longer.

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  • Is Muriatic Acid Safe For Swimming?

Yes If you follow our directions:

  • Always 30-60 mins for the acid to disperse before swimming in your pool
  • Check the pH of your pool is between 7.2-7.4
  • Does Muriatic Acid Affect Cyanuric Acid?

CYA and MA can be used in your pool with minimal adverse effects on each other. But, like any chemical, it’s best not to abuse these substances in your pool by mixing them.

Instead, you should add the chemicals separately waiting a few minutes in-between adding.

It’s always best to add small amounts of chemicals at a time. Then retesting with a pool test kit will ensure you don’t overdo it, which could cause additional problems.

  • Is Muriatic Acid the Same as Hydrochloric Acid?

MA and hydrochloric acid are basically the same thing. Muriatic acid is simply a watered down version of hydrochloric acid. It does not cost as much as hydrochloric acid since it’s not pure.

Although in the pool industry, the names muriatic acid and hydrochloric acid are often used interchangeably. They both do the same job and lower pH and alkalinity.

Author: Howard S. Baldwin

My name is Howard S. Baldwin. I am a work-at-home dad to three lovely girls, Jane + Hannah + Beauty. I have been blogging for the last 3 years. I worked for other Home and Lifetsyle blogs, did hundreds of product reviews and buyers’ guides. Prior to that, I was a staff accountant at a big accounting firm. Needless to say, researching and numbers are my passion. My goal is to be an informative source for any topic that relates to DIY life and homemaking.

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