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How to remove cyanuric acid from pool water

How to remove cyanuric acid from pool water How to remove cyanuric acid from pool water


The tried-and-true way to remove cyanuric acid is to drain the pool. If, for example, the pool has 200 ppm cyanuric acid, then an 80% drain and refill ought to bring the pool to a desirable 40 ppm cyanuric acid.

It’s important to recognize that doing two 40% drain and refills will not achieve this result.

For example, if the pool has 200 ppm cyanuric acid, a 40% drain and refill will bring the pool to 120 ppm cyanuric acid. Doing another 40% drain and refill will then bring the pool to 72 ppm cyanuric acid. It will then take an additional 40% drain and refill to get to about 43 ppm cyanuric acid.

That’s 40% more water used to achieve close to the same result.

CYA reducers

There are currently two manufacturers that market products that may reduce cyanuric acid. The products utilize microorganisms that consume cyanuric acid.

These special microorganisms perform their hydrolysis reactions so quickly that cyanuric acid levels may be restored to normal levels in days.

With Bioactive Cyanuric Acid Reducer, the microbes are chosen for their specific resistance to chlorine, and are said to withstand normal chlorination levels while they break down cyanuric acid.When the cyanuric acid begins to level off, chlorine can be reintroduced to the pool and the microorganisms will be destroyed.

The product is designed for pools with cyanuric acid levels above 100 ppm. According to the manufacturer, such a pool could expect levels to drop to within 40 to 60 ppm within 72 hours at 70 °F.

The product is supposed to work by accelerating a natural cyanuric acid degradation pathway resulting in only a fleeting formation of by-products that quickly convert into nitrogen gas. The nitrogen then harmlessly out-gasses from the water.

It is recommended to maintain normal chlorination levels while using this product because higher levels reduce its efficacy.

Natural Chemistry recently came out with a cyanuric acid removal kit. It is a two-part system to remove cyanuric acid from the water. Step one involves adding a chemical which neutralizes chlorine, bringing it to the optimum range for the cyanuric acid removal process. Step two removes the cyanuric acid with bioactive organic compounds.

If you’ve tried Bio-Active Cyanuric Acid Reducer or Natural Chemistry’s CYA Removal Kit, be sure to tell us what you think.


One possible method of reducing cyanuric acid that has recently come to fore is the use of alum, or aluminum sulfate. While there are no published scientific studies that indicate that alum can be used for cyanuric acid removal, the idea is gaining traction within the pool and spa service industry, with many service technicians reporting success on various Facebook group pages such as 14 PSI and Talking Pools.

The idea was first publicly introduced to the industry by CPO instructor Rudy Stankowitz during The Great CYA Debate at the International Pool | Spa | Patio Expo on November 6th, 2019.

Stankowitz has hypothesized that the reaction might be similar to the formation of a purple precipitate of copper cyanurate, which occurs when the concentration of copper is excessive in swimming pools. In this case, however, Stankowitz speculates that aluminum cyanurate may be formed.

Precipitates of aluminum cyanurates are discussed in an article entitled Cyanuric Acid and Cyanurates, Russian Journal of Coordination Chemistry, Vol 28, No 5, 2002 pp 301-324. The authors reported that reactions between aluminum chloride and cyanuric acid produced several white poorly soluble compounds, and aluminum cyanurate was among them, so, there might be something to the alum method of cyanuric acid removal.

As many have pointed out, however, more studies are necessary to determine exactly what is occurring in the pools where pool technicians are reporting success with alum.

The Alum-CYA Removal method calls for lowering pH to 6.8 to 7.0, adding alum at 8.3 lbs. per 10,000 gallons of pool water, mixing until the floc forms and settles to the bottom, and vacuuming to waste about 12 to 14 hours later.

If you’ve tried using alum to reduce cyanuric acid, be sure to tell us about your results.

Cyanuric Acid Reducers & Removers

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