Cyanuric acid is used in pools because of its ability to shield chlorine from being broken down by sunlight. But this benefit comes with a cost: A slight but measurable decrease in the rate of chlorine’s algicidal and antimicrobial activity and a downward shift in the calcium carbonate saturation index.

When cyanuric acid levels rise beyond about 90 ppm, industry standards recommend partial draining and refilling pools.

But in areas where water is in short supply, or during times of drought, draining and refilling pools is frowned upon, and the practice casts the pool industry in a bad light, giving the impression that the industry is environmentally wasteful.

That’s why there’s a need for more conservation-conscious alternatives that do not involve the water loss associated with draining. Nanofiltration/reverse osmosis is a viable alternative, and there are also specialty products ranging from polymers to active microbial cultures one may use to try to address the problem.

There are seven well-known ways to reduce cyanuric acid. They are:

• Drain and refill the pool.

• Nanofiltration/reverse osmosis: A kind of ultra-filtration.

• Polymer pillow: Made by GreenStory Global, this cyanuric acid remover is a filter that sits in the skimmer basket. The filter pouch is filled with carbon and a proprietary resin that absorb cyanuric acid from the water.

• Microorganisms that consume cyanuric acid, made by both Bioactive and Natural Chemistry.

• Alum: A pool flocculant composed of aluminum sulfate (Al3SO4).

• Melamine: A test reagent for cyanuric acid.

• Hyperchlorination: Excess chlorine.

Each of these methods has its benefits and drawbacks. Draining and refilling is a sure-fire way to remove cyanuric acid, but wasting water is exactly what we’re trying to avoid.

Reverse osmosis also works, but it involves cumbersome and highly expensive technical equipment.

The polymer pillow is effective for routine maintenance, but it is not quick — it may take weeks or longer to see results.

Users of microorganisms report mixed results. The products are very sensitive to variations in temperature, pH, and chlorine, which must be optimized to achieve the desired reduction in cyanuric acid.

That brings us to the final three: Alum, melamine, and hyperchlorination.

Melamine Method — This method is based on the same chemistry that is used in the cyanuric acid turbidity test. Melamine complexes on a 1:1 reaction ratio with cyanuric acid to form a filterable, suspended solid in increasing proportion to the amount of cyanuric species and melamine present.

The melamine method is an efficient way to reduce cyanuric acid, and it’s straightforward, too.

Start by determining the cyanuric acid concentration. Then apply the following dosage formula: (Volume of the pool in gallons ÷ 120,000) × (excess CYA) = melamine pounds to add. After adding the melamine to the pool, allow the water to circulate and then remove the resultant precipitate with a cartridge or DE filter.

Melamine reacts quickly with cyanuric acid and is readily filterable. Cons: It is expensive (prices and availability vary by grade) and not easy to find.

Hyperchlorination Method — As used in manufacturing processes that require removing cyanuric acid from water, this hyperchlorination method was described in 2001 in the Journal of the Swimming Pool and Spa Industry by John Wojtowiz of Chemcon. Cyanuric acid/cyanurate is oxidizable. The primary oxidation byproducts when using hypochlorite include nitrogen gas (N2, which offgasses), carbon dioxide gas (CO2, some of which offgasses and some which forms carbonic acid in solution), as well as some nitrates, chloride and water.

This method is also straightforward. Start by determining the cyanuric acid concentration. Then add a calculated dose by using the formula: (Volume Reduce

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of the pool in gallons ÷ 30,000) × (8 × excess CYA) = Amount of 10.3% sodium hypochlorite to add in quarts. Add soda ash to bring the pH to between 9 and 10. Then wait.

The trouble with this method is that it takes a lot of chlorine.

For example, with a standard 15,000-gallon pool and a cyanuric acid level of 100, it would take about 60 gallons of liquid chlorine to bring the cyanuric acid down to 40 ppm. It also takes more time than the other methods. Other drawbacks include the potential to bleach organic components in the pool and oxidize heavy metals. Care should be taken in colored pools, where the plaster pigments may be organic or when the pool water contains appreciable amounts of copper or iron that could be precipitated.

That brings us to the final method: Alum floc. The average pool service professional is already comfortable using alum as a flocculant, so it’s reassuring to know that it also works to reduce cyanuric acid.

Alum Floc Method – As developed and promoted by Florida pool pro Rudy Stankowitz, this method is based on the flocculation properties of aluminum sulfate and the purported complexing of cyanurate with aluminum ions.

As provided by Stankowitz, the method is as follows: 1. Adjust pH to 7.0 (Critical).

2. Adjust Total Alkalinity to 80 to 120 ppm, Calcium Hardness to 200-400 ppm, Water Temperature to 70 °F to 90 °F (Critical).

3. Ensure the pool is free of heavy debris that could stir the ‘floc’ upon vacuum to waste.

4. Test Cyanuric Acid level.

5. Filter Preparation: 6. Sand & DE Filters: With the pump off, manipulate the multiport valve to ‘Recirculate’ position.

7. Cartridge Filters: With the pump off, remove the filter element and then reassemble without it.

8. Broadcast Aluminum Sulfate at a rate of 8.33 pounds per 10,000 gallons of water.

9. Set timeclock to run the pump for two hours and then shut off. Remove the ‘ON’ tripper from the time clock to avoid unintentional circulation.

10. Allow the pump to remain off for a minimum of 12 hours. Do NOT allow the pump to run again until the entire process is complete and elements replaced with valves in the correct run positions.

11. With a portable vacuum system, vacuum the floc to waste at a pace slow enough not to stir or ‘break’ the floc.

12. Test residual aluminum level (should be < 0.2 ppm).

13. Test Cyanuric Acid level. Points of interest: The research and consulting group onBalance evaluated this method in their lab, and they were able to achieve approximately 15 to 20 percent reduction, measured by turbidity testing. When evaluated in the residential pool environment, where the process included floc and water removal/ replacement in the “vac-to-waste” process, they were able to achieve a 25-percent reduction in cyanuric acid Strengths: It’s fast (about a 24-hour process), and it’s simple.

Weaknesses: It involves the use of equipment in the vac-to-waste process. The reaction is chemistry and temperature dependent. There is some water loss. Compared to melamine and hyperchlorination, alum removed the least amount of cyanuric acid.