Magazine article Parks & Recreation

New CDC Data on CYA Levels in Pools

Magazine article Parks & Recreation

New CDC Data on CYA Levels in Pools

Article excerpt

Municipal pools started taking direct control of pool chemistry back in the early 1980s. At that time, most were using either gas chlorine or simple erosion feeders with trichlor tablets. Few owners and operators were concerned about Cryptosporidium (Crypto) outbreaks, and there was very little research and very few published guidelines for Crypto.

Now, fast forward to 2016, where, in the municipal pool industry, both of these chemical treatment technologies have become virtually extinct. However, Crypto, linked to major disease outbreaks and even patron fatalities, has wreaked havoc in multiple U.S. cities. The Centers for Disease Control and Prevention (CDC) published a fecal accident guideline in May 2001, and new 2015 data finally clears up a 30-year-old debate on proper treatment strategies. It concludes that high stabilizer levels (with manual cyanuric acid (CYA) introduction or with trichlor tablets) may delay Crypto inactivation and thus be very harmful to patrons.

With this data, we now have all the tools, and must do the following, to formulate a cohesive game plan for safer swimming:

* Understand CYA and the new 2015 research on CYA's impact on Crypto (http://pubs.acs.org/doi/ abs/10.1021 /acs.est.5b00962).

* Be aware of improved CYA testing strategies.

* Use a proper treatment strategy with correct stabilizer levels.

* Follow CDC protocol for fecal accidents.

* Educate staff and be prepared to take action.

CYA Review

Stabilizer or CYA is a pool chemical that is available either as a standalone powdered or granular specialty chemical, or as a byproduct of chlorine tablets or shock treatments. Once in the water, it protects the chlorine molecule from destruction by sunlight. Its concentration is expressed in parts per million (PPM) and can be tested and verified using a variety of chemical test kits.

All chlorine types have a chemical byproduct, with some more beneficial than others. Trichlor, in granular or tablet form, contains 55 percent CYA. When added to pool water, the chlorine is consumed almost immediately, but the CYA accumulates and is only removed via water leaks, splash out, backwashing or proactively dumping water. In a typical 50,000 gallon pool, CYA would build up at a rate of 7.33 PPM per day. CYA can also be handfed (and overdosed) using powdered or granular stabilizer, and only 8.5 lbs. will raise the CYA level in the same pool by more than 20 PPM. Why is this important? CYA in higher concentrations overprotects the chlorine molecule from UV rays and germs alike, simultaneously delaying inactivation of the Crypto pathogen that could harm your patrons.

What Is the Optimum CYA Level?

While many Department of Health (DOH) codes specify a maximum stabilizer level of 100 PPM, best-practice maximum levels on a national basis are thought to be closer to 30-50 PPM. In the early 1980s, a national group of early Oxidation Reduction Potential (ORP) pioneers used early research to promote a 20-30 PPM maximum range for commercial pools, with an 8-10 PPM target for highly used municipal pools and waterparks. Using these CYA ranges, a facility could maintain 750-775 ORP levels with only 2 PPM of chlorine--both representing a high level of performance with minimized operational costs.

Now, in consideration of an acceptably quick Crypto kill, new 2015 CDC data points out that the optimum level of CYA is around 8 PPM to see the following benefits:

* Retain 84 percent of CYA's UV protection of the chlorine molecule

* Achieve high ORP levels using moderate chlorine residual

* Remediate a fecal release in only 6. …

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