Feature Article - July 2018
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Come On In, The Water's Fine!

Effective Systems to Maintain Water Quality

By Deborah L. Vence

As aquatic facilities are well into the summer season, keeping pool water clean and safe is a top priority on a day-to-day basis. Special systems are necessary in order to keep water balanced and eradicate bacteria that can cause illness.

As pointed out on the Centers for Disease Control and Prevention (CDC) website, "Recreational water illnesses (RWIs) are caused by germs and chemicals found in the water we swim in. They are spread by swallowing, breathing in mists or aerosols of, or having contact with contaminated water in swimming pools, hot tubs, waterparks, water play areas, interactive fountains, lakes, rivers or oceans. RWIs can also be caused by chemicals in the water or chemicals that turn into gas in the air and cause air quality problems at indoor aquatic facilities."

To combat RWIs, pool facility operators need to make sure they have the best systems in place in order to efficiently manage water quality, and be aware of other factors that can play a part in water quality problems.

Necessary Systems for Water Quality

"For the past 100 years, swimming pool water quality was maintained by two systems: maintaining proper disinfectant levels and filtering the water via a circulation system," said Tom Lachocki, CEO of the National Swimming Pool Foundation (NSPF), a nonprofit organization in Colorado Springs, Colo.

"Today, most new large public pools have a third system in the construction specifications. The third system is a supplemental oxidizer or disinfectant. The most common ones used are either ultraviolet light or ozone. These supplemental systems help oxidize contaminants and inactivate pathogens that they contact," he said.

What's more, system automation that links water chemistry testing and chemical addition also is being adopted in large numbers.

"Advances in electrochemical probes have helped more accurately and precisely measure disinfectant and pH," Lachocki said. "The probes are connected to a controller that signals the chemical feeders. Thus, the automated systems help facilities maintain proper water chemistry with less manual labor and cost. Several studies conducted by the Centers for Disease Control & Prevention (CDC) working with health department data show that many higher-risk pools regularly do not have the proper disinfectant and pH.

"As a result," he added, "the standard of care is to include chemical probes, controllers and automatic feeders in higher-risk environments like public spas, kiddie pools, splash pads and others."

Another trend Lachocki mentioned relates to the people who are responsible for operating public pools.

"The standard of care is that public pools are under professional supervision by certification holders from a reputable nonprofit," he said. "All the systems in the world won't keep the pool safer if the people running the pool don't understand the basics. In today's litigious world, [having] trained and certified operators is a critical part of the system that protects the public and the facility."

Juliene Hefter, executive director and CEO of the Association of Aquatic Professionals, noted that "Proper water quality starts with the proper equipment for filtering and chemically treated water."

She said a pool operator must first know the chemical makeup of their source water. "Once that is known, they are able to choose the best disinfectant and pH adjuster to use for their specific water makeup," Hefter said. "Once the system is up and running, the importance turns to water balance to ensure proper water treatment as well as the extended life of your pool equipment and fixtures."

The three main areas that have an impact on water quality are filtration, circulation and disinfection, said Kevin Post, principal, Counsilman-Hunsaker, an aquatic engineering and design firm in St. Louis. "Filtration is the process of removing small particulates and contaminants," he said. "Disinfection is the process of inactivating microorganisms and oxidizing contaminants. A pool system must both disinfect and filter to have proper water quality."

He said filtration is affected by the media of the filter. "Typical filter media for pools includes cartridge, sand or perlite (or DE)," he explained. "While sand is inexpensive and effective, perlite can remove a much smaller particulate and, therefore, achieve a higher level of water clarity."

Circulation is important, too, to make sure the water is being filtered and treated. "The two areas to look for with circulation [are] the turnover time and the distribution of the water. The turnover time is the amount of time it takes for one full volume of pool water to pass through the filter system," Post said.

Pools with heavy bather loads will require a faster turnover to maintain proper water quality.

"The distribution of the water is also key to make sure the pool doesn't have 'dead spots' where the water is not moving and, therefore, does not get filtered or treated as often," he said. "Proper placement of return inlets will reduce and eliminate any dead spots. A pool dye test can help determine if your pool has any dead spots."

A blog post on pool dye tests on Counsilman-Hunsaker's website indicated that "After a pool is constructed, and prior to receiving operational permit, a non-permanent, non-staining colored dye is added to the pool's surge tank or skimmer systems. Almost immediately, dye will be seen returning through the pool's inlets. The pool will quickly turn a purple hue and you can easily see how all the water distributes within the pool. After approximately 10 minutes, the entirety of the pool should be colored and the test is complete. A short while thereafter, the dye will disappear when chlorine is added back into the pool."

For the most part, Post noted, "all commercial aquatic facilities are required to have a halogen in the water for instant sanitation," with the most common types being "sodium hypochlorite (liquid chlorine), calcium hypochlorite (tablet chlorine), bromine (non-chlorine sanitizer) or saline (on-site chlorine generator)."