Dissolved Oxygen In Aquaculture

- Apr 17, 2020-

It is said that fish farming raises water first, so what is water raising? Keeping water is nothing more than controlling various physical and chemical indicators in the aquaculture water body to provide a comfortable environment for aquaculture animals within a reasonable range, but there are so many physical and chemical indicators in the aquaculture water body, such as: ammonia nitrogen, nitrite, pH value, sulfurization Which one of hydrogen, dissolved oxygen, temperature, etc. is the most important?


1. Understanding of dissolved oxygen in ponds

Dissolved oxygen is simply explained as oxygen dissolved in water. Water is composed of water molecules, and there are gaps between water molecules. For example: add a little salt to a glass of water, the volume of water will remain the same. If you add a little more, it will remain the same. If you add salt, it will not dissolve, which means it is saturated. The dissolved oxygen in the pond is also the same. Oxygen and water molecules are fused together. When the oxygen is too much, it will be supersaturated and the oxygen will overflow. The aquaculture animals are also susceptible to air bubbles. The more the better. However, when the pond is hypoxic, anaerobic respiration of the water quality and harmful bacteria in the pond easily deteriorates the water quality and aquatic animals get sick. More than 80% of aquaculture problems are related to dissolved oxygen in ponds, and preventing hypoxia in ponds is one of the important ways to prevent disease.

dissolved oxygen test meter

2. Where does dissolved oxygen come from?

There are many sources of dissolved oxygen in ponds. In general, the main source of dissolved oxygen in aquaculture ponds is aquatic plants (including phytoplankton and large grasses) in the water to produce oxygen under photosynthesis under sunlight. Under normal circumstances, if the phytoplankton biomass in the water body is moderate, the pond will not be anoxic. The dissolved oxygen produced by phytoplankton can account for 80% or more, so keeping water is the key measure to prevent pond anoxia. The second is the aerator. The principle of aerator is to break the water molecules and let the water molecules come into contact with the air to dissolve the oxygen in the air. Therefore, the aerator can be exposed to the water when the dissolved oxygen in the pond is high. Oxygen, and we all use the aerator as a "lifesaving machine" in actual production. In fact, this is not a manifestation of the rational use of the aerator. We should use the aerator to adjust the water quality, so that the algae in the water body produce oxygen Because the dissolved oxygen produced by phytoplankton can account for 80% or more.

do test tube

3. What is the consumption of dissolved oxygen in the pond?

The most oxygen-consuming in the pond is the microorganisms in the pond, including the microorganisms in the sediment, phytoplankton and zooplankton, and sometimes too much algae or "water spiders" in the water can also cause severe hypoxia. It's our farm animals that consume oxygen. Sometimes the fish in the pond is too hypoxic, and some people think that it is caused by the hypoxia caused by the fish, and then sell the fish to a part of the hypoxia without change. In general, the most dissolved oxygen in the water body is the sediment in the pond, so what we often say to improve the bottom is actually a large part of the reason is to reduce the oxygen consumption of the sediment.

4. How to increase the dissolved oxygen in the pond? 

How to increase the dissolved oxygen in water? According to the above analysis, from the perspective of improving the dissolved oxygen in water, one is to cultivate phytoplankton (algae), and the other is to open the aerator. From the perspective of reducing dissolved oxygen in water, one is to reduce the oxygen consumption of sediments, and the other is to control algae and zooplankton in water. As long as these aspects can better grasp aquaculture animals, they can grow better and have fewer diseases.

do electrode  

5. Types of aerators 

The common types of aerators are: impeller aerator, waterwheel aerator, surge aerator, water spray aerator, microporous aerator, etc. 

1. Impeller aerator: agitating water (water lifting), aeration, aeration, suitable for ponds over 1.5 meters; 

2. Waterwheel aerator: Promote water flow and oxygenation, mainly applicable to the pond or bait station around 1 meter;

3. Surge aerator: The water stirring (water lifting) ability is better than the impeller aerator, but the aeration effect is general, and it is mainly used with other aerators at noon on a sunny day to achieve the effect of "bottom change";

4. Water-spraying aerator: Oxygenation, mainly used in small low-density seedling ponds;

5. Microporous aerator: mainly used in ponds with high density and high dissolved oxygen requirements. 

do analyzer

6. How to use the aerator?

1. The growth period of aquaculture animals. When a fish lacks oxygen, it will be greatly affected by itself, generally manifested as anorexia and morbidity. Therefore, when the food intake is large, the aerator should be turned on early to avoid hypoxia;

2. It opens at noon on a sunny day. For example, the water quality is too thick, and the dissolved oxygen is very high, especially when the dissolved oxygen reaches 30mg / l on noon and afternoon in sunny days. It is very dangerous to open the aerator at this time. The pond aerator should be turned on early instead of waiting until the dissolved oxygen is too high at noon.

3. Open when the weather changes. When the weather changes, it is easy to cause the algae in the pond to change or even cause the algae to die, so this time should open more aerators. Opening more aerators can not only reduce the toxic and harmful substances produced by the death of algae, but also promote the growth of new algae in the water body.

4. Open when windy. This depends on the situation. Some people say that wind energy can increase oxygen. We often see that the lack of oxygen increases after windy. In fact, this is mainly because the strong wind stirs up the organic matter in the pond, so it should be more when windy Note the lack of oxygen.