[Oxygenation method] Commonly used oxygenation methods in fish ponds to compare pond water oxygenation precautions
1. Principles and usage of several oxygenation methods
1. Chemical oxygenation. It is mainly because some chemical preparations are artificially put into the aquaculture water body, which will release oxygen by chemical action in the water after meeting water, thereby increasing the content of dissolved oxygen in the water body. The chemical oxygenates are generally sodium peroxycarbonate, peroxygen Any one of amide, calcium peroxide, hydrogen peroxide and ammonium peroxodisulfide, oxygenation is its main and most basic effect. It is used more and more in production practice, especially in Tangkou where electricity is difficult, water source is inconvenient, and there is no aerator, or in the rainy season, sultry, thunderstorm, high temperature, changeable weather, and frequent occurrence of hypoxia in floating head In most cases, this method is used. Ponds with high-density farming methods, especially shrimps such as green shrimp, Macrobrachium rosenbergii, and Penaeus vannamei, are prone to lack of oxygen in summer, leading to floating heads. Farmers always keep some chemical oxygen enhancers in case of unexpected events. The use of chemical oxygen enhancers mainly adopts the whole pond or local spraying. The specific amount of use depends on the type of drug and the occasion of use. The farmers should decide according to the manufacturer.
2. Mechanical oxygenation. The dissolved oxygen in the water body is increased mainly by providing high-content water body to the aquaculture water body through fishery machinery or by continuously supplying oxygen to the water body through effective contact between the water body and the air. The mechanical oxygenation methods are mainly in the form of water pump, aerator and blower microporous pipeline oxygenation.
⑴The water pump is the most traditional auxiliary oxygenation tool. Mainly when the pump is working, the centrifugal force generated by the impeller in the pump rotates at a high speed to pump the water to the pump body, so that the water generates a certain pressure and is pumped out from the pump outlet. By increasing the contact area between the water body and the air, the oxygen in the air is infiltrated. Therefore, the oxygen-enhancing effect is proportional to the degree of contact between water and air, and is also proportional to the pumping of oxygen-rich upper water (the water inlet extends too deep into the water layer, the inhaled water will have less dissolved oxygen, and the oxygen-enhancing effect will be poor.). When using a water pump to fill the pond, the water pump should be flushed high, and a water drop board should be added at the falling water. On the one hand, it reduces the scouring damage of the water flow to the pond slope, on the other hand, it expands the contact surface between water and air, and increases the oxygen entering the pond. The specific use method is: change every 15 days in spring and autumn, every 5-10 days in summer high temperature season, change the water in a small amount and several times, adopt the method of first draining and then filling, avoid large-scale irrigation and large-scale irrigation, and change every time The water accounts for 10%-15% of the pond. Generally, the water intake time is 1-4 o’clock, and in the early morning of cloudy and rainy days, depending on the specific situation, choose to add water in the afternoon on sunny days to form a certain water body micro-flow to keep the water quality fresh.
⑵The most widely used aerators are the impeller type and the waterwheel type. The impeller aerator is the most widely used one in recent years. When working, the impeller rotates, stirs the water body, produces water splash, and the centrifugal force generated by the rotation makes the upper water body diffuse to the periphery, and the lower water body fills the shortage to form an up and down circulation of the water body. After the surface water with high oxygen content enters the bottom layer, it can effectively improve the dissolved oxygen status of the bottom water body. It is usually used in ponds with a water depth of 1.5-2 meters, and is mostly used for the cultivation of four major carp such as herring, grass carp, bighead carp and silver carp. The basic aerator per kilowatt of power of the waterwheel machine is to agitate the water on the surface of the water body to increase its contact with the air, thereby achieving good oxygenation and promoting the flow of the water body. It is suitable for shallow ponds, mainly for shrimp , the cultivation of famous and premium aquatic products such as Penaeus vannamei. The operation method of the aerator is operated according to the requirements of “three on and two off”: that is, it is turned on for 2-3 hours at noon on a sunny day, at 4-5 o’clock in the morning on a cloudy day, and in the middle of the night when the rain is continuous or there are signs of floating head; generally not in the evening. Turn on, do not turn on during the day when it is cloudy and rainy.
⑶ Microporous pipe oxygenation is a new type of oxygenation method worthy of promotion. The principle is to send oxygen-rich air into the gas pipeline through the Roots blower, and the gas pipeline sends the air into the microporous tube. Directly to the bottom of the pond, from the bottom of the pond upwards to the water body to supplement oxygen. During the oxygenation process, rotational motion and up-and-down convection of the water flow can be caused. The upper and lower convection of the water flow brings the oxygen-rich water in the upper layer into the bottom layer, and at the same time brings out the harmful gas in the bottom layer; the rotating motion of the water flow diffuses the oxygen-rich water around the microporous tube outwards, realizing the uniform oxygenation of the whole pool water. . The supporting power of the microtube aerator per mu is 0.22 kilowatts. Generally, 20 acres are equipped with a blower of about 3.5-4 kilowatts, plus a total air supply pipe (PVC pipe) with an inner diameter of 75 mm and a microporous pipe with an inner diameter of 12 mm. Installation method: Set up the main air supply pipe in the middle of the pond, 30-50 cm above the pond, and run through the entire pond in a north-south direction. On both sides of the main gas supply pipe, a microporous pipe is set horizontally at an interval of 10 meters, one end is connected to the main gas supply pipe, and the other end is extended to 1 meter away from the edge of the pool, and the microporous pipe is fixed at 10 meters away from the bottom of the pool with bamboo stakes. -15 cm.
3. Biological oxygenation. Refers to planting an appropriate amount of aquatic plants at the mouth of aquaculture ponds suitable for planting aquatic plants (such as shrimp, river crabs, fish, etc.) or artificially increasing the amount of phytoplankton in the water body, and absorbing the water body through the photosynthesis of aquatic plants and phytoplankton. The carbon dioxide in the water is released to achieve the purpose of oxygenating the water body.
(1) Aquatic plant species are: bitter grass, elegans, black algae, water peanuts, water spinach, green grass and so on. Generally, it is planted according to the growth characteristics of organisms, and the area of aquatic plants accounts for 30%-40% of the area of the pond.
(2) The artificial application of biological fertilizers makes the higher oxygen-producing algae in the water body (the green algae are Chlamydomonas, Chlorella, etc., and the golden algae are Phonoflagellates). , Monoflagellate, etc., diatoms are needle-shaped rhomboid algae, Chaetoceros algae, etc.) become dominant populations.
Second, the advantages and disadvantages of several oxygenation methods
1. Advantages and disadvantages of chemical oxygenation.
Advantages: It is generally used in the mouth of the pond when it is difficult to electrify and acute floating head occurs, using chemical oxygenates to reduce stress and improve efficacy , the oxygenation effect is fast. According to clinical experience, when using insecticides and other fish medicines, chemical oxygen enhancers can be sprinkled, which is conducive to the rejuvenation of aquatic animals such as fish, shrimp and crabs.
Disadvantages: (1) Large amount of use, more labor, and higher cost. It can only be used to rescue the floating head of fish. It needs to be equipped frequently during the breeding period. Improper placement can easily reduce the effect. (2) It should not be used in the pond where the fry are cultivated to prevent the occurrence of bubble disease in the fry. (3) Excessive use of chemical oxygenates can easily cause harm to fish, shrimp and crabs.
2. The advantages and disadvantages of mechanical oxygenation.
Advantages: ⑴The aeration of the water pump is to add oxygen to the aquaculture water at the same time, which plays a multi-effect role. (2) In addition to adding oxygen, the aerator also has the functions of stirring water and aeration, promoting the reproduction and growth of plankton and improving the primary productivity of the pond. (3) Compared with the traditional impeller type and waterwheel type aerator, the microtube aerator has the functions of multi-point uniform oxygenation, safety, energy saving and water saving.
Disadvantages: (1) It can only be used when the power supply is smooth. For example, in a remote area away from industrial electricity, the cost of setting up a circuit is high. (2) The machinery is exposed to the air all the year round, easily exposed to wind and rain, and the machinery is damaged due to long-term contact with the water surface. It needs to be repaired regularly, and the maintenance cost is high. (3) The oxygen-enhancing area of the aerator is limited to a certain area, which is a single-point aeration. The dissolved oxygen content at the bottom of the pond is low, and the noise due to mechanical operation is large. Up, long-term use, a vortex will be formed under the body.
3. The advantages and disadvantages of biological oxygenation.
Advantages: (1) Plants absorb carbon dioxide in the water body and release oxygen through photosynthesis. At the same time, when plants grow, they need to absorb some nutrients in the water body. It has the effect of improving water quality and bottom quality. (2) Planting plants in some shrimp and crab ponds can also help shrimp and crabs to escape the heat, shell and eat.
Disadvantages: water plants are easy to grow wildly, which affects the illuminance of the pond. ;”> Three, matters needing attention when using the above oxygenation methods
⑴. When using disinfectants, insecticides and When using microbial preparations, care should be taken to increase oxygen to prevent hypoxia accidents.
⑵. To add oxygen to the pond through the water pump, be sure to observe the water quality of the water source in other rivers. For the polluted river water, it should not be injected into the pond.
⑶. When a large number of crustaceans such as shrimps and crabs molt, they need a quiet environment. Therefore, the use of mechanical oxygenation should be avoided as much as possible to prevent Affect the molting and cause molting death, resulting in economic losses.
⑷. When using the aerator to increase oxygen, it is required to regularly check the operation of the equipment, especially to prevent oil pollution from entering the aquaculture water and polluting the water quality and affecting the quality of aquatic products . At the same time, it is necessary to reasonably determine the start-up and operation time in order to give full play to the efficiency of the aerator.
⑸, the use of biological oxygenation, must require a certain degree of fertility in the water body to ensure the growth of aquatic plants and phytoplankton, while controlling the zooplankton in the pond amount to keep phytoplankton in abundance. In ponds with good aquatic plants, a drag knife should be used to cut off part of the aquatic plants in time, and the pond should be removed, and the “well” channel should be opened to make the aquatic plants dense and reasonable, and the coverage rate should be maintained at about 60%. removal to prevent deterioration of water quality. scientific farming.
