A Delicate Balance

The growing attraction of waterparks and interactive aquatic play features provides lots of fun and excitement for families. Children especially enjoy the unique play features and bubbling water actions in the safe comfort of shallow water. But it is a daily balancing act for pool operators to maintain healthy venues. These facilities present a distinctive set of water-quality issues, and require constant monitoring. Because of the sheer size, complexity and number of visitors at waterparks, the risk factors are increased versus traditional pool environments.

Recreational water illnesses (RWIs) are the number-one health concern at aquatic play features, lazy rivers, activity pools and water slides/flumes. RWIs are introduced into the water environment by bathers, due to lack of bather cleanliness. Cryptosporidium, Giardia, E.coli 0157:H7, Norovirus and Shigella are the major threats. The water features attract children, who are too young to control the effect of their own fecal contamination, so parents need to be continually educated. Thus, pool operators must shoulder the responsibility by ensuring there is a constant supply of adequate disinfectant to curtail bather infection.

Making Adjustments

To maintain healthy water chemistry, operators need to make continual adjustments to accommodate high bather loads. Additionally, the introduction of makeup water as a result of splash-out and evaporation will affect the chemistry.

Water-chemistry guidelines impose a constant, free, available chlorine range of 2.0 to 4.0 parts per million (ppm); however, the activity of the chlorine depends on the pH of the water. The higher the pH, the less active hypochlorous acid becomes. Conversely, a low pH is not recommended, due to the corrosive properties which harm equipment and surfaces, and also create eye burn. The National Swimming Pool Foundation recommends maintaining a pH within an ideal range of 7.4 to 7.6. A chlorine range of 2.0 to 4.0 ppm and a pH range of 7.4 to 7.6 are common chemical parameters; however, operators must follow local codes and regulations outlined by individual state and local departments of health and environment.

By The Numbers–Manual Or Automatic

Based on the increasing disinfection demand in interactive aquatic play features, many state and local health departments have amended their codes to include specific guidelines for these bodies of water. These include automatic control systems (controllers) to monitor the disinfectant and pH levels at all times. In addition, automatic chemical-feed systems work in conjunction with the controllers, adding the recommended amount of disinfection and pH adjustments in order to provide the proper level of sanitation.

These facilities receive a constant influx of fresh water as a result of splash-out and higher bather loads; thus, the demand for sanitizer is higher than in traditional pools. Water features are hard to manage, and most codes now require Oxidation Reduction Potential (ORP) devices to measure the activity of the chlorine. ORP relates to the oxidizing/reducing capability of the water by measuring the electron activity. The ORP probes only measure the ratio of oxidation. The electron activity is measured in millivolts (mV), and the recommended range is 650 mV to 750mV. ORP is only an indirect method to approximate disinfectant level. Also, ORP measurements are influenced by the fluctuations in pH readings. It is important that the operator calibrate the probes as part of a routine maintenance schedule because residue will build up on the probes and provide false readings. These are some of the reasons that manual testing with a DPD test kit is also required to ensure bather protection.

Improving Disinfection With Newer Technology

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