Problem Solver - August 2008
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Preventing RWIs and Shutdowns at Your Aquatic Facility

According to the U.S. Centers for Disease Control and Prevention, there are around 360 million visits to recreational water venues annually. But at the same time, recreational water illnesses (RWIs) represent a rising concern among the public and among pool operators.

Results from a recent survey (conducted by NSF International) showed that 92 percent of aquatic facility inspectors surveyed shut down a recreational water facility within the past three years. Poor water quality was cited as the most common reason for the closures. To reduce the risk that your facility will be shut down due to poor water quality—or even worse, that you will see an RWI outbreak—it is imperative to educate yourself and your staff on the best equipment and methods to keep your water clear and safe.

Q: Our outdoor facility includes a conventional lap pool as well as a zero-depth entry play pool. Do different types of pools require different kinds of attention?

A: The traditional approach to chlorination may need rethinking for new pool designs such as spray features and zero-depth entry pools. Because sunlight causes chlorine to dissipate from the pool, shallow bodies of water—with a high percentage of their water close to the surface—are more susceptible to chlorine loss from UV rays. And, whether you are dealing with an indoor or outdoor facility, bather load impacts chlorine usage. Shallow pools typically have less water volume per swimmer and thus potentially less chlorine per swimmer.

Think about it: Deep water acts as a chlorine reservoir. For example, when several people swim on the surface of a regular swimming pool, chlorine is consumed at the surface due to sun exposure or bather waste. However, some of the chlorine in the deeper water will circulate to replace it. In a shallow body of water, once the chlorine is used up, it's gone.

Q: How can I be sure I'm getting the right amount of chlorine into the water at all times?

A: No matter which type of pools your facility contains, you should size a chlorinator large enough to deliver plenty of chlorine during peak demand. In the case of indoor pools, heavy bather loads cause pools to use more chlorine. With regard to outdoor pools peak bather loads often occur during the heat of the day (when the sun is already destroying chlorine) and an under-sized chlorinator can't keep up. This could lead to low chlorine residual and cloudy water. Your pool may consume 80 percent of all its chlorine in just a few hours under these conditions.

The solution is to rely on a larger chlorinator. Using a high-capacity chlorinator does not necessarily mean you'll spend more money on chlorine—you'll just be able to deliver the right amount of chlorine to the water when it's needed, meeting those peak demand requirements. This way, your chlorinator won't be playing catch-up overnight, and your patrons' health will be better protected.

Q: What should I know about cyanuric acid?

A: To begin with, don't add cyanuric acid or use products that contain it, such as trichloroisocyanurate tablets (trichlor), in indoor pools. Cyanuric acid slows down chlorine's dissipation from sunlight. And too much of it will inhibit chlorine's effectiveness. No sunlight, no need.

When added to outdoor pool water, cyanuric acid (stabilizer) will help maintain a chlorine residual, but just like medicine, you don't want to take more than is really required or adverse affects may set in. That said, 10 to 20 parts per million is all you'll need.

Without stabilizer, chlorine can dissipate from your outdoor pool in as little as an hour or two. Any chlorinator will have trouble keeping up with that pace, especially if your pool's circulation turnover time is greater than four hours. By using stabilizer within the levels mentioned above, you provide better protection to your swimmers and consume less chlorine.

Q: What else should I be concerned about?

A: Because maintaining proper chlorine levels is so critical, you'll want to be sure your equipment meets NSF Standard 50. For example, NSF tests cal-hypo chlorinators and specific branded tablets to confirm that they can do what the manufacturers claim they can do: feed a specific amount of chlorine, measured in pounds per hour.

In addition to being aware of standards, it is also important to ensure that your staff is well-trained. No matter what else you do, you'll want your people to be able to identify a problem. Having some of your pool staff attend Certified Pool Operator or Aquatic Facilities Operator Certification training is a good idea. In addition, you should establish and enforce a regular routine for testing pool water, and keep your logbook up to date, accurate and in a designated location.

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