The aerator is a machine that is often used in fish farming. Its main function is to increase the oxygen content in the water to ensure that the fish in the water will not be hypoxic. At the same time, it can also inhibit the growth of anaerobic bacteria in the water and prevent the deterioration of the pond water from threatening the living environment of the fish. Aerators-generally rely on its own air pump to pump air into the water to achieve the purpose of increasing the oxygen content in the water.

The main performance indicators of the aerator are specified as aeration capacity and power efficiency. Aeration capacity refers to the amount of oxygen that an aerator adds to the water per hour, in kilogram-hour; power efficiency refers to the amount of oxygen that an aerator consumes 1 kilowatt-hour of electricity to increase water, and the unit is kg/kWh. For example, a 1.5-kilowatt waterwheel aerator, with a power efficiency of 1.7 kilowatt-hours, shows that the machine consumes 1 kilowatt-hour of electricity and can add 1.7 kilograms of oxygen to the water body. Although the aerator is used more and more widely in aquaculture production, some fishery practitioners still don't understand its working principle, type and function, and it is blind and random in actual operation. Here it is necessary to understand its working principle first, so as to master its use in practice. As we all know, the purpose of using aerators is to add dissolved oxygen to the water body, which involves the solubility and dissolution rate of oxygen. Solubility includes three factors: water temperature, water salt content, and oxygen partial pressure; dissolution rate includes three factors: the degree of unsaturation of dissolved oxygen, the contact area and method of water-gas, and the movement of water. Among them, the water temperature and the salt content of the water are a kind of stable condition of the water body, which is generally unchangeable. The degree of unsaturation of dissolved oxygen is the factor that we want to change, and it is also a current state of the water body. Therefore, it is necessary to increase oxygen to the water body

It is necessary to directly or indirectly change the three factors of oxygen partial pressure, water-gas contact area and method, and water movement status. In response to this situation, the measures taken when designing the aerator are:

1) Use mechanical parts to stir the water body to promote convection exchange and interface update;
2) Disperse the water into fine mist droplets and spray them into the gas phase to increase the water-gas contact area;
3) Inhale through negative pressure to disperse the gas into micro-bubbles and press them into the water.

Various types of aerators are designed and manufactured according to these principles. They either take one kind of measures to promote oxygen dissolution, or take two or more measures.