A Delicate Balance
Creating the ideal chemistry at waterparks
By Connie Sue Centrella
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
Protecting bather health is a critical concern for operators, facility management and the respective regulatory agencies. Supplemental equipment is now being offered or mandated to improve disinfection. Ozone, ionization and ultraviolet technologies have gained acceptance as a means of enhancing bacteria kill. Ozone is a powerful oxidizer, and has proven to inactivate bacteria and viruses resistant to chlorine, such as cryptosporidium and Giardia. Ozone O3 is generated by the exposure of oxygen molecules to a high-energy electrical discharge. The oxygen atoms unite with other oxygen molecules to produce O3. This technology is known as Corona discharge (CD). Ultraviolet light can also be used to create ozone at lower concentration levels. Operators should review their local codes for the recommended application of ozone. Both systems have demonstrated an ability to reduce chloramine levels through oxidation. Chloramines, the by-product of chlorination, are formed when chlorine kills bacteria, or combines with organic material.
Chloramines create a strong chlorine odor, eye and skin irritation and corrosive conditions on the surface of the water features. They have also been found to contribute to poor air quality at indoor facilities.
Water Balance Is More Than Measuring pH
Waterpark chemistry does not end with the measurements of disinfectants and pH. Water balance also includes alkalinity, calcium hardness, temperature and total dissolved solids. Joined with pH, these five factors optimize the disinfection process, protect feature surfaces, and provide longer equipment life. These balancing factors are influenced by bather waste, disinfectants, source water, airborne debris, aeration and evaporation. Most standard commercial test kits measure total alkalinity, calcium hardness, pH and chlorine/ bromine residuals. Waterpark operators must also understand and factor in the effect of temperature. A thermometer should be placed at various locations in the water feature. Operators should record and calculate the water balance regularly to monitor changes. An effective tool to determine water balance is the Langelier’s Saturation Index. This calculation will help operators determine if the water is out of balance, causing corrosion or scale and potential equipment damage. Being proactive in water balance will ensure cost savings in the future.
Keeping A Log
Creating a maintenance log is crucial in waterpark operations. The log should record daily readings of water-balance factors, as well as an observation of pool-surface and equipment conditions. Here are 10 action items to be implemented.
1. Use a professional test kit with fresh reagents, and store in a cool, dry environment.
2. Manually test the water from various locations within the waterpark.
3. Periodically test the makeup water to foresee the effect on pool-water balance.
4. Understand the characteristics of the disinfectant and its influence on water chemistry.
5. Maintain water-balance factors:
a. Total alkalinity, 80 to 120 ppm
b. Calcium hardness, 200 to 400 ppm
c. pH, 7.2 to 7.8
d. Cyanuric acid (if used), 30 to 50 ppm
e. Chlorine residual, 2 to 4 ppm (halogen residuals are greater in interactive water features--consultlocal/state codes for regulation).
6. Examine all equipment, and check the automatic chlorine probes for residue buildup. Clean if necessary.
7. Maintain instructional records of all control and chemical-feed equipment.
8. Keep a booklet with the Material Safety Data Sheets for all chemicals used.
9. Develop a chemical-safety handling program, and train all staff on steps to take in case of a chemical spill.
10. Train all staff on RWIs and emergency-response actions to take if a diarrhea accident occurs.
A casual attitude toward water chemistry in waterparks can create risks and lead to an unhealthy and unsafe environment for bathers; this also creates a potential liability and loss of business for the facility. Higher bather loads, greater turnovers and shallower water contribute to unclean and unsanitary conditions. Actively testing the water, both manually and electronically, will aid in prevention of undesirable bacteria and organics. Operators need to know and understand that interactive water features and aquatic play features are not just another swimming pool; they contain a significant, new set of parameters, and staff should be trained in order to achieve the optimum safe environment.
Connie Sue Centrella is a professor and Program Director for the online Aquatic Engineering Program at KeiserUniversity eCampus. She is a four-time recipient of the Evelyn C. Keiser Teaching Excellence Award “Instructor of Distinction.” Centrella is an industry veteran with over 40 years experience in the pool and spa industry. She is a former pool builder with extensive knowledge in pool construction and equipment installation as well as manufacturing.