By Marcelle Dibrell
For years, the pool and spa industry has been searching for a way to reduce cyanuric acid concentrations without draining and refilling the pool, but many of the choices offered are expensive.
So it should come as great news to the industry that alum — a commonly used, inexpensive flocculant — has been shown to measurably reduce cyanuric acid levels.
The pool industry research and consulting group onBalance has recently concluded an extensive series of laboratory and field tests that confirmed a method proposed by a pool service professional several years ago.
In 2019, Rudy Stankowitz of Aquatic Facility Training & Consultants in Florida told the pool and spa industry that using alum was an effective way to reduce cyanuric acid. He made the announcement during “The Great CYA Debate,” which took place at the International Show that year, and the idea was swiftly met with a degree of skepticism and derision.
At the time, Stankowitz claimed he could achieve a 50-percent reduction over three days.
Removing cyanuric acid using Alum Floc method. Pictured above: Flocculation using Alum; Vaccuming to waste; Filter Effluent. Alum method developed by pool industry instructor and author Rudy Stankowitz. onBalance’s results were more modest, but still appreciable.
“In our experiments, we can consistently obtain a 25-percent reduction in CYA using Rudy’s method,” said Que Hales, who conducted the research.
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 100 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.
But the average pool service professional is already comfortable using alum as a flocculant, so it’s reassuring to learn that it also works to reduce cyanuric acid.
Stankowitz says he landed on the idea around 2019 while listening to news stories of California’s 7-year drought. It got him thinking about pool maintenance challenges in that area, such as how to manage high levels of total dissolved solids, calcium, and cyanuric acid.
“I started thinking about copper and cyanuric acid, how they complex, precipitate from the water, and result in blotchy copper cyanurate staining. So I wondered what would happen with other metals,” Stankowitz said. “But who wants to have metals in their pools? That moved my thoughts to aluminum, because we remove it when we use it as aluminum sulfate as a flocculant in a vac-to-waste.”
There’s science to support the possibility of using alum (which contains aluminum ions) to floc cyanuric acid out of water.
Such a reaction is mentioned in a 2002 article entitled “Cyanuric Acid and Cyanurates,” which appeared in the Russian Journal of Coordination Chemistry. The authors reported that reactions between aluminum chloride and cyanuric acid produced several white, poorly soluble compounds, and aluminum cyanurate was among them.
And producing a poorly soluble compound is just what we need if we want to vacuum it out to waste.
But until now, no one had measured exactly what kind of cyanuric acid reduction the alum method could achieve.
So onBalance has been lab and field testing the alum method, as well as a couple other methods that service technicians may want to know about.
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:Apool 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 absolutely works, but it involves cumbersome and highly expensive technical equipment.
The polymer pillow is effective for routine maintenance, but it is not quick — it takes weeks 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. onBalance tried each of these methods and quantified their results.
Here is the scoop on how to do them, if they worked when onBalance tried them, and what the research group sees as the strengths and weaknesses of each one.
Alum Floc Method – As developed and promoted by 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 200400 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: a. Sand & DE Filters: With the pump off, manipulate the multiport valve to ‘Recirculate’ position. b. Cartridge Filters: With the pump off, remove the filter element and then reassemble without it.
6. Broadcast Aluminum Sulfate at a rate of 8.33 pounds per 10,000 gallons of water.
7. 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.
8. 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.
9. With a portable vacuum system, vacuum the floc to waste at a pace slow enough not to stir or ‘break’ the floc.
10. Test residual aluminum level (should be < 0.2 ppm).
11. Test Cyanuric Acid level. Points of interest: When onBalance evaluated this method in their lab, 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.
Stankowitz and others have reported higher reductions, including up to 50 percent. Environmental and chemical factors may have varied in those pools.
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 the other two tested methods (melamine and hyperchlorination), alum removed the least amount of cyanuric acid.
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. Here is what onBalance tried: 1. Determine Cyanuric Acid concentration.
2. Apply the following dosage formula: (Volume of the pool in gallons ÷ 120,000) × (excess CYA) = melamine pounds to add.
3. Add the melamine dose to the pool water.
4. Allow for full blending and for the reaction to go to completion. In a circulating pool this typically will be about 15-20 minutes.
5. Run the circulation continuously to allow for filtration and to maintain the solid in a suspended state. Brush settled material as needed.
6. Remove the resultant suspended solid using a cartridge or a DE filter. In their testing, onBalance found that the pool will typically be clear after 4-6 turnovers.
7. Re-test the Cyanuric Acid in the pool to verify the target concentration has been reached.
Points of interest: When onBalance evaluated this method in their lab and in the onBalance demo pools, they were able to achieve greater than 90-percent reductions in cyanuric acid, measured by turbidity testing. In most cases, the target reduction should be to achieve the “ideal range” of 20-30 ppm cyanuric acid concentration in the pool, rather than attempt to remove it all.
Overdosing the melamine will result in an excess residual of melamine in the pool water.As a result, any further additions of cyanuric acid (either as raw cyanuric acid or as a result of tri- or dichlor addition) will result in the production of additional clouding with filterable suspended solid (melamine cyanurate) until all of the melamine has been complexed and removed via filtration.
The melamine cyanurate complex is readily filterable using a cartridge or a DE filter. Afterward, the complex is easily removed from the filter element. There is no leftover melamine or melamine-cyanurate compound left in the water because it is all filtered. Disposal of the removed complex may or may not become a disposal issue.
Strengths: It is very fas t ( approximately ½ hour for complexing and inside 24 hours for filtration depending on turnover rate), and it’s very easy.
Weaknesses: In the quantities needed for a typical pool, melamine is very expensive and difficult to get.
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. It is based on the heterocyclic amine ring structure of cyanuric acid/cyanurate. This organic structure 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. Here is what onBalance tried: 1. Determine Cyanuric Acid concentration.
2. Calculate dose by using the formula: (Volume of the pool in gallons ÷ 30,000) × (8 × excess CYA) = Amount of 10.3% sodium hypochlorite to add in quarts.
3. Add the calculated dose and blend it thoroughly into the pool water. This may be achieved by brushing, circulation, etc.
4. Adjust the pH to 9-10 using sodium carbonate (soda ash) or sodium hydroxide (caustic soda/lye).
5. This reaction occurs faster in warmer water.
6. Wait (Allow the reaction to proceed: May be hours to days.)
7. Re-test the Cyanuric Acid to ensure the process is successful.
Points of interest: When onBalance evaluated this method in their lab, as well as in the onBalance demo pools and in residential swimming pools, they were able to achieve as much as 90-percent reductions in cyanuric acid after the requisite reaction/ contact time, measured by turbidity testing.
The actual concentration of chlorine is a variable. Increasing amounts of chlorine over longer periods result in greater cyanuric acid reductions. The target is 8 times more chlorine than cyanuric acid.
In most cases, the target reduction should be to achieve the “ideal range” of 20-30 ppm cyanuric acid concentration in the pool.
Strengths: It’s very easy. There’s no need to filter or vacuum.
Weaknesses: 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 requires more time than the other methods. There is 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.
