Using Lake Fountains For Aeration & Healthy Aquaculture
By: Randy Hine
The dynamics of oxygen production and use in a pond are complex and can be difficult to quantify. Plankton and algae in the water can produce some oxygen, but basing the oxygen consumption on only the organisms you are raising in the pond or lake will lead to under estimation, as wild organisms will inevitably occupy the same body of water. This leads to a need for sufficient aeration, and it has been shown that a fountain style or aerator is much more efficient than a paddle aerator, especially in brackish water. Pond aeration can make the difference between a swampy, stinking mess, and a healthy, thriving aquaculture with high production.
The dissolved oxygen concentration in water changes continuously and it can be difficult to predict how much aeration any given body will need, but the rule of thumb is that a smaller body, or a polyculture, will need greater aeration. The more organisms such a catfish, prawns, or crayfish, the more oxygen is consumed. Also, pond aeration is more important during the night, as the oxygen producers in the water are more active during the day. Studies have shown that some production is possible in a pond with no aeration, but that will more than double when aeration is applied to the water (Pond Aquaculture Water Quality Management by Boyd and Tucker). The limiting factor in a pond is not the feed, but the aeration.
In using lake fountains, it is best to place them on the side of the lake or pond where the prevailing winds are coming from. This carries the droplets out over the water and each drop brings its cargo of oxygen. Special attention should be paid to aeration during the warmest months of the year, as water holds less oxygen as it heats up. Other factors that can lead to a need for increased aeration are algae die-off, sick fish, and increased concentrations of ammonia or nitrates. These may necessitate installation of portable aerators during times of stress to the aquaculture. Fish tend to concentrate where the oxygen levels are the highest, so multiple lake fountains will not only improve aeration, but spread the concentration out allowing room to feed and grow.
Randy Hine writes about aquaculture, lakes and pond maintenance for www.herrmannsfishfarm.com. He has a particular interest in Pond Aeration Systems and lake fountains.
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