A pond contains three basic types of bacteria, each of which contains several different micro-organisms. While some types of bacteria are harmful, most are beneficial to the wildlife and plant life that inhabit ponds. Without certain types of bacteria, ponds would become overridden by algae and other fungi, which would render their water cloudy and putrid. The right balance of bacteria helps to maintain optimal life-supporting conditions in ponds.
Ponds need aerobic bacteria to ensure their water quality remains in good condition. These bacteria multiply when oxygen is present. Aerobic bacteria are important for algae growth. Ponds need algae to generate oxygen, and bacteria need oxygen to manufacture carbon dioxide. Carbon dioxide is necessary to maintain the life of the plants that are supported by the pond. Aerobic bacteria tend to live in shallow ponds with a depth of just a few feet. This is because shallow ponds allow sunlight to penetrate the entire pond and cultivate the growth of algae.
Anaerobic bacteria jeopardise a pond's water quality and make it smell bad. They discharge hydrogen sulphide and methane gas, which produce toxic water conditions. Anaerobic bacteria consume nutrients but at a slower pace than aerobic bacteria, causing algae and fungi to grow more rapidly. They live and thrive in ponds and other waters that lack oxygen. Pond decomposition sets in when the ratio of anaerobic bacteria exceeds the amount of good bacteria present in the pond. Anaerobic bacteria inhabit ponds with depths of 8 to 10 feet or greater, where sunlight is unable to reach the bottom and therefore promote algae growth. The presence of anaerobic bacteria is usually visible by a layer of green scum appearing on the pond's surface.
Facultative bacteria are most often found in ponds of medium depth, usually 5 to 6 feet. They thrive in pond environments where anaerobic bacteria line the bottom and aerobic bacteria live near the surface. Facultative bacteria are basically suspended in the middle of the pond's water depth. They need oxygen to grow and reproduce, though less than aerobic bacteria. These bacteria are most adaptable to changeable pond conditions, and they work to keep anaerobic bacteria from decaying the pond.