Creating Chemistry

For water parks and aquatic play features

By Connie Sue Centrella

One of the fastest growing segments in the aquatics industry is water park developments that utilize aquatic play features. These are designed for play and recreation with shallower depths, high-moving water velocities, aerating pumps and special effects, such as sprays, misters and waterfalls. Although some may consider these swimming-pool environments, there are unique differences in the way in which the water quality is managed.

A New Breed

Water chemistry parameters in these facilities should depend not only on bather loads, but on environmental characteristics. Leisure-rivers channel water through a series of flumes--usually narrow--and in some instances through areas covered with foliage and trees. This plant life provides algae and phosphates, which can create poor clarity as well as moss, mold and mildew within the flumes.

Wave pools create some unique challenges due to the shallow water at the entry points. Because of the high bather load and shallow water depths, the challenges to the water chemistry are maintaining water clarity and continuous feeding of sanitizer to maintain a residual. The sunlight draws the chlorine gases out of the shallow depths at a greater speed than in traditional pool environments.

Interactive play features, such as misters, sprays, water jets and sprinkling, are extremely popular attractions, and some existing pool facilities are incorporating these devices during renovation. The main concern is providing adequate hydraulics to maintain circulation through the filter systems and inducting enough sanitizer to maintain the water free of contaminants and bacteria.

Management of these aquatic play features requires a constant review of all chemical parameters. Due to the high bather loads, the aquatic operator should understand that the water must be maintained, clear and sanitary; without constant controls, the water will become cloudy and create a greater risk for recreational water illnesses. It will also make it difficult to see a bather in distress, thereby causing safety issues.

Follow The Rules

My first recommendation is to review the makeup water and determine the chemical composition. Since there is a high evaporation rate as well as splash-out occurring in these play facilities, maintaining the water level is usually done through automatic fill devices. The makeup or fill water changes the water balance, and may have an effect on the ability of the sanitizer to efficiently kill bacteria.

According to the new Aquatic Play Feature Handbook, published by the National Swimming Pool Foundation, the addition of an adequate chlorine feeder is of the utmost importance in wave pools. Chemical feed rates in traditional swimming pools are inducted at a rate of one-quarter to one pound of elemental chlorine per 1,000 gallons of pool water per day. In a large pool, such as a wave pool, this would equate to the need for chemical feed pumps that could add 350 to 500 pounds per day. The feeders should be designed to treat for the maximum bather loads. Caution: during evening hours these feeders may provide excessive residuals if not adjusted. Lowering feed rates in the evening hours will offset improper chemical additions and save operation dollars.

Automated chemical feeders should be designed to contribute the essential chemical sanitizer as well as balance chemicals to control the pH, alkalinity and calcium hardness. Chemical feeder injection points should be located within the return lines at positions which do not allow interference with other chemicals. Some of these feeders have the capability to test the water and send a message to the feeder to induct more chemical to maintain water balance; therefore, the location of the probes is essential. However, these are just a few points in the circulation system. Manual testing should be done because various points within the feature will provide different test readings. More frequent testing should be done in aquatic play features than traditional pool environments. (Aquatic operators should periodically remove and clean the probes and examine for calcium/scale on the probes. Buildup on the probes may lead to an inaccurate reading, thus water balance will not be achieved.)

Swimmer Beware

Because of the heavier bather loads as well as an abundance of children playing in and around the water, the conditions are ripe for recreational water illnesses. Cryptosporidium, Giardia and E.coli 0157:H7 are the three major RWIs and occur when there is a fecal accident in the pool.

Chemical Solutions

Chlorine is still the preferred sanitizer for public pools and bathing places. However, the ability to relieve the pool of chloramines (combined chlorine) may be a challenge. Systems that aid the disinfection processes are ozone and ultraviolet devices. Ozone is an excellent oxidizer and will aid in the elimination of chloramines.

Ultraviolet (UV) systems reduce chloramines by photo-oxidation. When bacteria are exposed to the UV lamp, this high energy literally damages the protein structure of the bacteria, and it is chemically altered so that the organism can no longer reproduce. Because the bacteria are diminished, they cannot spread throughout the aquatic feature. However, a word of caution here is that with both ozone and UV, there must be a chlorine residual present at all times.

Additional feeders can be installed, such as pH adjusters, acid feeders and carbon dioxide. The ability to maintain the proper pH is directly related to the pH of the sanitizer. Trichlor tablets have a low pH (2.9), which results in a lower pH in the water; conversely, calcium hypochlorite compounds (pH of 8.5 to 11) and sodium hypochlorite (pH of 13) increase pH levels. The operator must know the pH of the sanitizer in order to effectively manage the water chemistry.

Chemical parameters for aquatic play features should be based on bather load, the environment and usage time; however, the ideal chemical parameter chart provides only guidelines as to where each chemical factor should range. These are traditional ranges and do not supersede local codes and regulations. The key parameters are chlorine 2 to 4 ppm; pH 7.4 to 7.6; total alkalinity 80 to 120 ppm; calcium hardness 200 to 400 ppm and cyanuric acid 30 to 50 ppm.

A casual attitude toward water chemistry in water play features may result in poor water clarity but mostly creates an unhealthy and unsafe environment for guests. High bather loads, greater turnovers and fill water conditions contribute to unclean water. Actively testing the pool water, both electronically and manually, will aid in prevention of undesirable bacteria. The acceptance of water-play features as an enjoyable recreation venue will continue to grow and bring joy and happiness to many people who traditionally did not visit swimming pools. Because of their design, further educational studies are recommended to enhance this future water-play enjoyment.

Connie Gibson Centrella is Program Director for the online Aquatic Engineering Program at Keiser College eCampus. She 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.