Principles and methods of use of several aeration methods

1. Chemical oxygenation.It is mainly artificially put some chemical agents into the aquaculture water body, which will chemically release oxygen in the water after encountering water, thereby increasing the content of dissolved oxygen in the water body. Chemical oxygenators are generally sodium peroxycarbonate and peroxygen. Any one of amide, calcium peroxide, hydrogen peroxide, and ammonium peroxodisulfide, oxygen enhancement is its important and basic effect. The amount of use in production practice is also increasing, especially in the tangkou where power is difficult, the water source is inconvenient, and there is no aerator, or in the rainy season, sultry, thunderstorm, high temperature, changeable weather, and frequent hypoxia. In cases, this method is adopted. High-density farming ponds, especially shrimps such as blue prawns, Macrobrachium rosenbergii, and Penaeus vannamei, are prone to lack of oxygen in summer and cause floating heads. Farmers often stock some chemical oxygenators to prevent accidents. The use of chemical oxygenators is mainly for whole pond or partial spraying. The specific dosage depends on the type of medicine and the occasion of use, and the farmers should decide according to the manufacturer.

2. Mechanical oxygenation. The main method is to increase the dissolved oxygen in the water body by providing high-content water body to the aquaculture water body through fishery machinery or continuously supplementing oxygen to the water body through effective contact between the water body and the air. Mechanical aeration methods are mainly in the form of water pumps, aerators, and blowers for aeration in microporous pipes.

⑴ Water pump is the traditional auxiliary oxygenation tool. Mainly when the water 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 In water, the oxygen-enhancing effect is directly proportional to the degree of contact between water and air, as well as the upper layer of water that is rich in oxygen (the water inlet extends too deep into the water layer, the inhaled water dissolved oxygen is less, and the oxygen-enhancing effect is poor.). To fill the pond with a water pump, the water pump should be raised to flush the water, and a drop board should be installed at the place where the water falls. On the one hand, it reduces the erosion and damage of the pond slope by the water flow, and on the other hand expands the contact surface between water and air to increase the oxygen entering the pond. The specific method of use is: change every 15 days in spring and autumn, and every 5-10 days in the high temperature season in summer. Change the water several times in small amounts and adopt the method of draining and then irrigating. Avoid large draining and large irrigation every time. Water occupies 10%-15% of the pond. Generally, the water intake time is 1-4 o'clock, early in the morning on cloudy and rainy days, depending on the specific situation. Choose to add water to form a certain water body microflow in the sunny afternoon to keep the water quality fresh.

⑵The widely used aerators are impeller type and waterwheel type. The impeller aerator is the widely used one in recent years. When working, the impeller rotates to stir the water body to produce splashes, and rely on the centrifugal force generated by the rotation to spread the upper water body to the periphery, and the lower water body fills up the water body to circulate up and down. After the surface water with higher oxygen content enters the bottom layer, it effectively improves the dissolved oxygen status of the bottom water body. It is usually used in ponds with a depth of 1.5-2 meters, and is ly used for the breeding of four major domestic fish such as herring, grass carp, bighead carp, silver carp, etc. The impeller aeration can meet the aeration needs of 3.8 acres of surface adult fish ponds. The basic aerator per kilowatt of power of the waterwheel machine is to stir the water on the surface of the water body to increase its contact with the air, thereby achieving good aeration and promoting the flow of water. It is suitable for shallow ponds and mainly used for blue shrimp , Vannamei white shrimp and other famous and special aquatic products breeding. The operation method of the aerator is operated in accordance with the requirements of "three openings and two non-opening": that is, turn on for 2-3 hours at noon on a sunny day, turn on at 4-5 am the next morning on a cloudy day, turn on at midnight when the rain is continuous or there are signs of floating heads; generally not in the evening Turn on, and do not turn on during rainy days.

(3) Aeration in microporous pipes is a new type of aeration that is worth promoting. The principle is to send oxygen-enriched air into the gas pipeline through the Roots blower, and the gas pipeline sends the air into the microporous tube. It is directly transported to the bottom of the pond, and the air is diffused from the bottom of the pond to supplement oxygen. In the process of aeration, it can cause rotational movement and up-down convection of water flow. The upper and lower convection of the water flow brings the oxygen-rich water from the upper layer to the bottom layer and at the same time brings out the harmful gases in the bottom layer; the rotating motion of the water also diffuses the oxygen-rich water around the microporous tube outwards, realizing the uniform oxygen increase of the whole pool water . The supporting power of the microtube aerator is 0.22 kilowatts per mu. Generally, 20 mu is 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: erect the main air supply pipe in the middle of the pond, 30-50 cm higher than the pond, and run through the whole pond in a north-south direction. A microporous tube is set horizontally at intervals of 10 meters on both sides of the main air supply pipe, one end is connected to the main air supply pipe, and the other end is extended to 1 meter from the side of the pool, and the microporous tube is fixed 10 meters away from the bottom of the pool with bamboo stakes. -15 cm.

3. Biological oxygenation. It refers to planting an appropriate amount of aquatic plants at the mouth of aquaculture ponds suitable for planting aquatic plants (such as blue prawns, river crabs, fish, etc.) or artificially increasing the amount of phytoplankton in the water body, through the photosynthesis of aquatic plants and phytoplankton, absorbing carbon dioxide in the water body, Release oxygen to achieve the purpose of increasing oxygen in the water body.
⑴ Waterweed varieties include: Vallisneria, Elodea, Hydrilla verticillata, water peanut, water spinach, Qingping, etc. Planting is generally based on the growth characteristics of organisms, and aquatic plants account for 30%-40% of the pond area.
⑵ Artificial application of biological fertilizers to make high-grade oxygen-producing monocytic algae in the water body (green algae is Chlamydomonas, chlorella, etc., golden algae is Phaeocystis, monoflagellate, etc., diatoms are needle-shaped Nitzschia, Chaetoceros Etc.) to become the dominant population.