Fish Not Foul—PVC Piping Is Critical to Modern Mega-Aquariums

Visitors to the huge Ocean Voyager exhibit at Atlanta’s Georgia Aquarium find a tank the length of a football field, containing 6.3 million gallons of salt water. They can see thousands of denizens of the open ocean, including whale sharks, the largest fish in the world. What they don’t see is the critical life support system that depends on 10 miles of PVC pipe.

“PVC helps keep the water healthy,” said Mike Hurst, vice president of engineering and operations. Water quality is crucial. Every exhibit is sampled three times a day, and the water in each exhibit is filtered completely every 60 minutes.  PVC’s greatest advantage is that is does not corrode, even though salt water is extremely corrosive, Hurst said. This means that pipes don’t fail or leak; it also means that the pipe material does not leach chemicals into the water that can affect the fish or plant life.

The Georgia Aquarium, which opened in November 2005, is the largest in the world. And because Atlanta is far from the coast, the operation makes its own synthetic salt water. “We treat it like gold,” Hurst declared. “Once we make it, we keep it indefinitely.” The closed system is continuously recycled and disinfected using dozens of filters.  PVC pipe connects every stage of filtration, including 54 sand filters as well as heat exchangers to keep the water at the right temperature, ozone generators for disinfection, sulfur denitrification systems to remove nitrates, which are toxic to fish, and de-aereation systems to remove carbon dioxide. Then PVC pipes return the water to the exhibit. The total flow for all these processes is 66,000 gallons a minute, Hurst said.

PVC is a key component of all of today’s aquariums, explained Paul Boyle, PhD, senior vice president for conservation at the Aquarium and Zoo Association, based in Silver Spring, Md. In fact, Boyle declared, two materials—acrylic and PVC—“have changed the face of public display designs of aquariums.” Thick, seamless, super-clear acrylic has replaced glass and allowed for much larger exhibits that, in turn, need clearer water and larger, more complex life-support and filtration systems. So PVC is now universally used, and has in many cases replaced metal, fiberglass, and other materials because it is non-corrosive, non-leaching, durable, and among the easiest to use and configure.

Because space is expensive, the idea is to design a compact system, and PVC allows this, Boyle said. Hurst agreed, that PVC is also easy to install, cut, and configure. “You can build a life-support system faster and more efficiently” with PVC than with other materials, he said, and “PVC requires a smaller turning radius, saving space in tight areas.”