Allen La Pointe is currently in his seventh year of work at the John G. Shedd Aquarium, and is presently the Water Quality Manager. He began working as a chemist at the Aquarium in 1997, learning the life support systems and working with the instrumentation. Two positions later, he now manages the water quality laboratory, monitoring animal habitats and making adjustments to life support operations.

In conjunction with the Shedd and the College of DuPage, Allen has designed and teaches a two-semester course in water chemistry, titled Water Works. The course topics include general water chemistry, water quality parameters, water cycles, water analysis, natural systems, aquarium chemistry, and aquarium life support systems.

Before starting his career with Shedd Aquarium, Allen was employed at the Hammond Indiana Sanitary District in a water analysis instrumentation position for three years. He studied aquatic zoology and chemistry at Southern Illinois University in Carbondale, receiving a B.S. in Zoology in 1993. Allen is currently working on a specialized Master's degree in Zoological Management.

ABSTRACT:

Dissolved Gases in Aquarium and Aquaculture Facilities.

Dissolved gasses, in the correct amounts, are extremely important for the animals that reside within aquatic systems. Many factors and water quality parameters are connected to the types and concentrations of gasses in solution. Likewise, other factors greatly influence the concentrations of dissolved gasses.

Oxygen saturation is dependant on temperature and the concentration of dissolved solids in the water. The required concentration of oxygen varies by a variety of factors, including species and age.

Fish hobbyists and professionals, to lower the pH or even to sedate fish, use carbon dioxide. Without proper gas exchange in a recirculating system, carbon dioxide can build up, affecting the carbon cycle and lowering the pH. This can also effect the concentration of other gasses in solution.

Each dissolved gas component exerts a pressure within the system. The sum of these pressures is the Total Dissolved Gas pressure (TDG). In a natural system, the TDG will form an equilibrium with the external pressure exerted up it, the Barometric Pressure (BP). When the BP increases, more gasses can dissolve in solution. When the BP decreases, the saturation for gasses decreases, and gasses will release from solution until the equilibrium is reestablished.

In open and closed recirculating aquaculture and aquarium systems, certain conditions are known to cause an artificial increase in the number of gases dissolved in solution. This in turn raises the TDG. Likewise, situations can arise where the BP drops quickly and the aquarium or aquaculture system cannot compensate quickly. In both of these scenarios, fish may develop Gas Bubble Disease, which is often lethal.