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Shrimp Farm Water Quality Management

Shrimp Farm Water Quality Management

Managing water quality is of utmost importance in shrimp farming operations. Good water quality ensures proper growth of shrimp and reduces mortality. Various water quality parameters such as salinity, hardness, temperature, dissolved oxygen levels, nitrite levels among others need to be adhered to for ensuring optimum production. It may be sound complicated however it is pretty easy to monitor these parameters using easily available test strips.

Dissolved oxygen

The optimum dissolved oxygen content of pond waters is about of 5 mgllitre. Aeration is a proven technique for improving dissolved oxygen availability in ponds. Various types of aerators are used for pond aeration. In heavily aerated ponds strong water currents can cause erosion of pond bottom. Therefore, placement of aerators in a pond should be considered carefully.

Often people include plants in the pond to keep the pond well-oxygenated. It should however be kept in mind that though they may release large amount of oxygen but in night they tend to taken all the oxygen which may cause fluctuation in oxygen levels. In warm weather the problem may get worse as warm water generally tends to have less oxygen.

The following steps help to alleviate the problem:

– Enhancing water circulation by using aerators.

– Reducing the stocking level.

– Removing the silt from the bottom of the pond as the bacteria that grow there consume a lot of oxygen thereby depleting dissolved oxygen levels so necessary for the shrimp population to thrive.

Temperature

Temperature determines the rate of shrimp growth. Water temperature can be adjusted to optimum levels in indoor shrimp hatcheries. It is difficult to adjust water temperature in large water-bodies. Aerators not only help in improving oxygen levels but also help in maintaining uniform temperature.

Turbidity

Turbidity results from several factors including suspended soil particles, planktonic organisms and through decomposition of organic matter. Turbidity resulting from plankton is generally desirable. However, excessive turbidity prevent heat and light penetration adversely affecting shrimp growth.

pH

pH is a measure of hydrogen ion concentration in water and indicates how acidic or alkaline is the water. The pH of water affects the metabolism and physiological processes of shrimps. pH also exerts considerable influence on toxicity of ammonia and hydrogen-sulphide as well as solubility of nutrients.

Total hardness

Hardness is an important factor for fresh water fish ponds. It should be ideally be greater than 40 mgllitre. Hardness helps to protect shrimps against harmful effects of pH fluctuation and metal ions. Ponds with relatively low hardness can be treated with lime to increase hardness.



Pond Aerator Systems

Pond Aerator Systems

Selecting Pond Aeration systems

Pond aerators are used to increase the level of dissolved oxygen in water. Water aerators are used to combat low oxygen conditions in lakes and ponds or in aquaculture tanks. Dissolved oxygen is a major indicator of water quality and a vital parameter in maintaining optimum productivity in shrimp and other fish farms. Grossly reduced oxygen levels may result in mass morbidity of aquatic life.

There are two common techniques to aerate a water body : surface aeration technique and subsurface aeration technique.

Natural Aeration

Natural Aeration results in surface as well as subsurface aeration techniques.

Surface aeration results from disturbance of the surface of water because of falling water such as from a falls, fountain or stream.

Sub surface aeration primarily occur via aquatic plants. Aquatic plants release oxygen into the water via the process of photosynthesis and thus support aquatic life.

Surface Aeration

Surface aeration is achieved via fountains, floating surface aerators and paddle wheel aerators.

Fountains help to enhance the aesthetic appeal of water bodies. However they are not so effective in increasing dissolved oxygen of a large water body in an appreciable manner.

Floating surface aerators work in a manner similar to fountains. Their ability to enhance oxygen levels are also limited. Further they do not enhance the appeal of water bodies as fountains do.

Paddle wheel aerators are most effective in increasing dissolved oxygen levels and as such they find maximum use in shrimp and other aquaculture operations.
They are powered by electric motors and mounted on floats. They are mostly used in outdoor shrimp farming.

Subsurface aeration

Subsurface aeration is achieved by means of diffused aerator systems. Diffused aerators utilise bubbles to oxygenate water. Bubbles are released at the bottom of the water body. As the bubbles rise to the top, aeration of the water body takes place.

Diffused aerators are classified into two types depending on the natures of bubbles they produce : course bubble generators and fine bubble generators.

Course bubble generators are generally much more inefficient in enhancing oxygen levels because of larger size of bubbles generated.

Fine bubble generators are extremely effective in enhancing oxygen levels. However one difficulty with fine bubble generators is that the diffusers may clog and therefore they need to be cleaned periodically to ensure their effectiveness. The problem is more in case the turbidity of the water is high. Fine bubble generators are frequently used in indoor shrimp farming.

Diffused aerators of various capacity depending on requirement may easily be obtained from Amazon.