Cyanuric acid is a chlorine stabilizer for swimming pools.
Cyanuric acid is a chlorine stabilizer for swimming pools. It is usually referred to as “stabilizer”. It should not be confused with muriatic acid which is often used to adjust the pH.
Cyanuric acid combines with free chlorine in pool water, protecting it from the sun’s ultraviolet rays and reducing chlorine loss. Properly managed, cyanuric acid can reduce the amount of chlorine needed to maintain the minimum chlorine residual in an outdoor pool. Many chemical suppliers recommend that the optimal range for cyanuric acid is 30-50 ppm, although a study published by the University at California at Davis1 , indicates that there is still significant savings in chemical costs with cyanuric acid levels as low as 2 or 3 ppm.
Lowering the hypochlorous acid concentration can have a significant impact on the rates of any reaction for which hypochlorous acid is involved in a rate limiting step. Specifically disinfection and oxidation of contaminants can be slowed by the lowered hypochlorous acid concentration.Generally speaking, the rate of disinfection or the rate of oxidation of a contaminant in the water by hypochlorous acid could be described by the following equation:
–dN/dt = k [HOCl]a N
N represents a microbial concentration (such as deduced by a plate count) of the microbe to be killed or the concentration of the oxidizable species (such as various organic compounds, breakpoint susceptible chloramines, sulfide, or nitrite) to be destroyed;
–dN/dt represents the rate of loss of the microbe or oxidizable material;
k represents a rate constant; a is a positive real number that is specific to the type of reaction involved; and
[HOCl] represents the hypochlorous acid concentration.
Application methods will depend upon the product form being used. Cyanuric acid is available in both granular and liquid slurry forms. Since the granular form is slow to dissolve, if it is fed into the skimmer, care must be taken to feed the product slowly to avoid blocking the lines. Most granular cyanuric acid products are approximately 100% active. The following table summarizes the cyanuric acid contributions from dichloro-striazinetrione and trichloro-s-triazinetrione.
For manufacture of chlorinated isocyanates. Its mainly used in synthesizing new type bleaching agent, resin, anti-oxidant, paint, coating, selective weedkiler and metal cyaniding slow corrodent. And it also can be directly used as swimming pool chlorine stabilizer,nylon, plastic, polyseter, fire-retardant agent and cosmetics additive.
When used, the ideal range for cyanuric acid is 30 – 50 ppm. The concentration should not exceed 100 ppm. Cyanuric acid is not recommended for indoor pools or spas where protection from sunlight is not necessary.The 100 ppm limit is a common consensus among health authorities, for example:
|State Standard||100 ppm|
There is a degree of uncertainty in setting this value, but the consensus decision is not entirely arbitrary. The following factors were considered when setting the limit for cyanuric acid:
- Effective use levels of cyanuric acid;
- Cyanuric acid/chlorine equilibria;
- Effect of cyanuric acid on Oxidation Reduction Potential (ORP); and
- Effect of cyanuric acid on chlorine kill rates.
Test kits and strips are available for testing the cyanuric acid concentration to ensure that it is within the proper range. If the cyanuric acid concentration needs to be reduced the following approaches may be used:
- Partially drain and refill the pool
- Increase backwash times or frequency
- Follow appropriate water replacement intervals
At above 50 ppm of cyanuric acid, the time it takes to kill bacteria in the water is longer compared to swimming pool water without cyanuric acid. Also, as the level of cyanuric acid builds up, the chlorine will become increasingly less effective in keeping the water clean and problems such as increased cloudiness and exceeding combined chlorine limits can occur.
- Cyanuric acid and stabilized chlorine (dichlor or trichlor) should only be used in outdoor swimming pools. It should never be used in indoor swimming pools, spas or hot tubs.
- Both dichlor and trichlor release cyanuric acid to the pool water. It is not necessary to put additional cyanuric acid into a pool that uses dichlor or trichlor.
- Pools that use cyanuric acid are required to maintain a free chlorine residual of 2.0 ppm.
- Cyanuric acid should be tested at least once a month.
- Cyanuric acid levels must be maintained below 100 ppm.
- Partially drain pool and add water to reduce cyanuric acid concentration.
Future & Benefit :
- Stabilizes chlorine to help prevent degradation of active chlorine by sunlight
- Also commonly known as “stabilizer” or “conditioner”
- May be added to the pool as CYA, sodium salt of cyanuric acid, or as the chlorinated forms of cyanuric acid, sodium dichloro-s-triazinetrione (dichlor) and trichloro-striazinetrione (trichlor)
- The effect of cyanuric acid on slowing the oxidation of organics, kill rates of bacteria, viruses, and algae has been demonstrated, primarily in laboratory studies. However, disease outbreaks linked to cyanuric levels in properly sanitized pools have not been reported.
- Cyanuric acid does not stabilize bromine sanitizers
- Cyanuric acid contributes to total alkalinity (See Alkalinity Information Bulletin)
In order to safely use and handle cyanuric acid products, all individuals involved in their manufacture, distribution, sale, or use should be trained and knowledgeable about their properties. Safety information is available on the product label, product MSDS (Material Safety Data Sheet), and manufacturer’s training materials. This safety information will include disposal instructions, instructions on disposal of the package, and spill response information.
For safety and handling information for stabilized chlorine compounds, refer to manufacturer’s labels and appropriate Information Bulletins. Cyanuric acid is stable when stored in a cool, dry, ventilated area and not contaminated by other chemicals such as bases or chlorinated pool chemicals. Cyanuric acid, dichloro-s-triazinetione and trichloro-striazinetrione, in the solid form or in concentrated solutions, shall not be mixed with other pool chemicals including other chlorinating agents. Partially empty packages must not be consolidated, as this could result in dangerous mixing with incompatible dry chlorinating agents having a similar appearance.
|Formula||C3 H3 N3 O3|
|pH (1% solution)||4|
|Moisture||0.5 to 0.50% max|
|Water Solubility @ 25°C||3 gram / 1000 ml|