POND AERATION
Dissolved oxygen analysis measures the amount of gaseous oxygen (O2) dissolved in an aqueous solution. Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid movement), and as a waste product of photosynthesis.
Environmental Impact:
Adequate dissolved oxygen is necessary for good water quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life forms. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills.
Dissolved oxygen concentrations may change dramatically with lake depth. Oxygen production occurs in the top portion of a lake, where sunlight drives the engines of photosynthesis. Oxygen consumption is greatest near the bottom of a lake, where sunken organic matter accumulates and decomposes. In deeper, stratified, lakes, this difference may be dramatic - plenty of oxygen near the top but practically none near the bottom. If the lake is shallow and easily mixed by wind, the DO concentration may be fairly consistent throughout the water column as long as it is windy. When calm, a pronounced decline with depth may be observed.
Seasonal changes also affect dissolved oxygen concentrations. Warmer temperatures during summer speed up the rates of photosynthesis and decomposition. When all the plants die at the end of the growing season, their decomposition results in heavy oxygen consumption. Other seasonal events, such as changes in lake water levels, volume of inflows and outflows, and presence of ice cover, also cause natural variation in DO concentrations.
A proper pond aerator is vital to having a healthy koi pond, water garden or lake no matter what time of year it is. Use a pond air pump during hot weather to provide the necessary oxygen. During the winter an air pump will keep an opening in the ice, add oxygen and help gas off toxins.
Any system will benefit from adding an aerator. An air pump will also help the growth rate of your fish, both koi and goldfish. Adding an aerator will also help the biological process within your pond. Biological filtration requires large amounts of oxygen so pond air pumps should be used.
Oxygen in ponds comes from two sources--photosynthesis and diffusion from the air. The most important source, photosynthesis, is the process plants use for manufacturing food. In the presence of sunlight, plants (especially algae) add oxygen to water as a by-product of photosynthesis. At night, no oxygen is produced, but respiration of algae, fish and bacteria continues to remove oxygen from the water. Most of the time there is a desirable balance between how much oxygen is produced and how much is used, but under some conditions, the balance can be upset, and the oxygen concentration becomes low enough to stress or kill fish. The amount of oxygen in pond water can vary considerably from pond to pond and from hour to hour. Typically, however, oxygen concentrations are lowest at dawn and highest during late afternoon.
The amount of oxygen water can hold is dependent upon atmospheric pressure, salinity and temperature. Water can hold less oxygen as altitude increases. Salinity is not important for most freshwater fish producers. The most important factor is water temperature. As temperature increases, water can hold less oxygen. Most low oxygen problems occur from June through September. The reasons for this are:
- Water can hold less oxygen as it becomes warmer.
- Respiration rates of both plants and fish increase with the warmer water, so more oxygen is used.
- Summer's still, hazy or cloudy days may reduce the amount of oxygen produced.
- Large amounts of feed given to fish at this time of year result in large quantities of fish waste which create a higher demand for oxygen.
TJB-INC offers several different styles of Areation Systems. Both for large ponds or lakes, and for smaller water gardens like the kind we would enjoy in our own backyard.
