The minimum depth of two feet is required to prevent the growth of root aquatic plants. Depths of over five feet may lead to an odor problem. The size of a stabilization pond is determined by the size of the population it serves and the anticipated BOD load. A rough approximation of anticipated need is 1 acre for every 2,500 persons served by the pond. When a pond size is over 6 acres, it should be divided in segments or cells.
Algal photosynthesis is the key element in the ecology of an aerobic stabilization pond.
Aerobic populations of bacteria supply carbon dioxide for algal growth, which is turn supply oxygen to the wastewater which helps to maintain the aerobic balance. Waste organics in the water are metabolized by bacteria. In addition, the pond may contain secondary feeders including protozoa, rotifers, and crustaceans. Because of this tendency to become anaerobic, most ponds occasionally emit odors. For this reason, ponds should be located as far as possible from existing or planned development areas.