Safe Water
The importance of clarity in wave pools
By David Keim
Photos: Aquatic Development Group
An essential factor in the safe operation of any pool is clean, crystal-clear water. This becomes increasingly important when one begins to consider wave-pool design and operation. With the inherent difficulties associated with surface turbulence and bather density, the clarity and purity of pool water become critical to the effectiveness of lifeguard observation and bather-disease control.
All the lifeguards in the world can be stationed around a pool, but if the turbidity of the water limits the ability to see below the surface, there is the potential for tragedy. The problem of maintaining water quality in a wave pool is compounded in almost every aspect of its design. The large water surface, large shallow area, and heavy bather loads contribute to a significantly higher level of airborne- and bather-carried contaminants than would be found in a conventional pool.
The Suntan Lotion Syndrome
The latter source of contamination becomes especially significant when one considers the number of patrons in a typical recreational wave pool over the course of a day. With an average guest stay of five to six hours, and the large expanse of lounge area adjacent to the pool, creating a “suntan lotion filtration syndrome,” any issues one might encounter in a commercial swimming pool are compounded when a move is made outside to the larger wave pools.
The high percentage of shallow water (less than 3 feet) in a wave pool, or kiddie pool for that matter, means the contamination per gallon of water is many times that of any other type of pool. All this tends to illustrate the inadequacy of most design standards for pool filtration, modeled around conventional pools and governed by applicable codes.
Under most circumstances, filtration based on a six-hour turnover rate as required by most health regulatory agencies, is enough to maintain acceptable turbidity levels in a typical pool. However, if a typical wave pool is compared to an indoor, eight-lane, competitive pool and the large surface area/suntan lotion syndrome associated with a wave pool is factored in, the industry is finding it would not be unusual for a wave pool to have contaminant levels as much as 50 times higher than those found in traditional lap pools. This important issue must be fully understood by operators. With the increased contaminant loads, it is necessary to increase the turnover rate and filter capacity to maintain the water clarity that is so necessary in a wave pool.
More Filtration Needed
What the industry is finding for similar six-hour filtration rates in both pools is it typically results in approximately 50 times as much filtration needed for a wave pool designed in accordance with existing swimming pool codes.
Instead, wave pool recirculation/filtration systems should be designed on the basis of a two-hour turnover rate. Admittedly, decreasing from a six-hour to a two-hour turnover represents a series of hurdles (one being a threefold increase in filter-system size and thus an increase in capital expenditure), but with proper upfront design, the increased capital costs need not be significant. Plus, the decrease in potential liability exposure makes for a prudent investment.
Water clarity is a must for the safe operation of a wave pool. The water capacity for a two-hour turnover rate is the best assurance of proper water quality, and expandable filtration capability affords the owner the most flexible and efficient means of accomplishing this.
David Keim is the director of Public Markets Business Development at Aquatic Development Group, a designer and builder of water parks and water-ride attractions. For over 50 years ADG has provided design/build and equipment services to more than 4,000 public, scholastic, resort, and amusement facilities worldwide. For more information, visit www.aquaticgroup.com.