Oxygenation and Aeration: Physics in the Fish Tank

摘要

One of my visions is to locate hatcheries and land-based fish farms where the highest operational costs are feed and labor - in that order. However, oxygen and power costs often find their way near the top of the list. In many operations, oxygen addition is a critical application — without it, fish may die in minutes. And without enough of it, adequately distributed through the culture tanks, fish may not feed well. Understanding the driving force behind oxygenation requires a brief foray into physics. Pressure is the driver. Gas pressure exists both in the air and in water. Each gas can be considered independently (for this purpose) to have its own "partial pressure." Air for example is about 21% oxygen and 79% nitrogen. A water sample containingoxygen at a level of 100% saturation would contain oxygen at a "partial pressure" equivalent to the "partial pressure" of the oxygen in the air. Total gas pressure is simply the addition of all the partial pressures of the gases present in solution (whether the solution be in air or in water).