How aquaculture users should choose oxygen generators

After a long period of development and improvement, aquaculture has evolved from extensive farming to high-density farming, which has increasingly higher requirements for dissolved oxygen in water. Therefore, the role of aerators is particularly important; an aerator is a mechanical device that transfers "oxygen" from the air to water quickly through working components driven by power sources such as electric motors or diesel engines, increasing the dissolved oxygen in water. Common types include impeller type, water wheel type, spray type, jet type, and aeration type.
Types such as water wheel type, spray type, jet type, and aeration type.

One,AeratorFunction of the aerator

The function of the aerator is to quickly transfer "oxygen" from the air into the aquaculture water body, increasing the dissolved oxygen content in the water; it can comprehensively utilize physical, chemical, and biological functions, not only solving the problem of fish surfacing due to oxygen deficiency in pond farming but also eliminating harmful gases, promoting water convection exchange, improving water quality conditions, reducing feed coefficients, enhancing fish pond activity and primary productivity, thereby increasing stocking density, intensifying the feeding of aquaculture targets, promoting growth, significantly increasing yield per acre, and fully achieving the goal of increasing aquaculture income.

Two, types, structure, and applicable range of aerators

(1) Impeller type aerator: There are many models of impeller type aerators, which can be divided into umbrella-shaped impellers and deep-water impellers, but the basic structure is consistent, mainly consisting of an electric motor, a gearbox, an impeller, support rods, and floats.
The main components are made of steel pipes, used to connect the float and the gearbox. An aerator uses three support rods, and some are also equipped with water level adjustment devices.
① Electric motor  
The power of the aerator usually uses Y series four-pole electric motors, with a power range of 0.75~3.0kW. The motor should be equipped with a rain cover that does not obstruct ventilation to prevent sun and rain exposure. The power line uses a three-phase four-pole rubber wire, and the motor terminal should be equipped with spring washers to prevent disconnection due to vibration.
② Gearbox: The function of the gearbox is to reduce the motor's speed so that a smaller power motor can drive a large impeller, increasing the water jump range.  

③ Impeller: The main body of the umbrella-shaped impeller is an inverted cone, with a partition added in the middle, welded or molded from steel plates.  

④ Support rod: All made of steel pipes, used to connect the float and the gearbox. An aerator uses three support rods, and some are also equipped with water level adjustment devices.  

⑤ Float: Currently made by blow molding, with three floats used for one aerator.

The impeller aerator has comprehensive functions such as oxygenation, aeration, and stirring of the water body, promoting high and stable fish production in ponds, and is widely applicable. It is currently the most commonly used aerator, with better oxygenation capacity and power efficiency than other types, but it operates with relatively high noise and is generally used in large-scale aquaculture ponds with a water depth of more than 1m.

(2) Water wheel type aerator
The water wheel type aerator mainly consists of five parts: electric motor, gearbox, frame, float, and impeller.
① Electric motor: The power of the electric motor is generally small, ranging from 0.5 to 1.5kW.
② Gearbox: Common types include turbine gear reducers, belt first-stage gear reducers, and second-stage gear reducers. Under the premise of Warranty of the motor quality, the quality of the gearbox determines the lifespan of a water wheel type aerator.

It should be equipped with a rain cover to protect the motor and gearbox while maintaining good ventilation; in addition, the gearbox should use oil splash lubrication and be strictly sealed, with regular replacements.

③ Frame: Used to support the weight of the entire machine, it must remain level and is generally welded from stainless steel square pipes. The bearing seat is made by injection molding, presenting a single concave support. Some products use phenolic cloth plastic bearings or nylon bearings, which have a long lifespan. The frame is also used to fix the machine in a certain position on the water surface, preventing movement due to water agitation or wind.
④ Float: Currently, many are made by hollow blow molding into boat shapes, and can also use polystyrene foam or fiberglass pipes. Generally, the model is heavier on the side of the electric motor and gearbox, so the sizes of the two floats are not the same. In addition, considering the torque generated by the impeller's stirring force on the machine body during operation, the support point of the impeller shaft on the float should be offset, so that the machine body maintains a slight tilt relative to the water surface when static. After starting, the frame remains basically parallel to the horizontal plane.

⑤: The impeller water wheel aerator can be configured with a single impeller, double impellers, or even triple impellers, and its structure is also diverse. Most single impellers are welded with several rows of angle iron on a cylinder, with the angle iron openings aligned with the rotation direction, distributed in a spiral pattern on the cylinder.
Currently, the common double impeller uses blade type, that is, 6 to 8 blades are installed on the wheel shell, with small or elongated holes on the blades to reduce weight and water resistance, and can create more splashes and water droplets. Currently, impellers are mostly injection molded.

At present, most double impellers are symmetrically arranged on both sides of the machine body and float, referred to as double output shaft type, which has better oxygenation and circulating effects of working water flow than single output shaft models with impellers placed between floats.
The water wheel type aerator can create directional water flow in the aquaculture pond while oxygenating, stirring water, and aerating, which is beneficial for the farming of eels and shrimp. It stirs the surface water with stirring plates, expanding the contact area between the aquaculture water body and the air, thereby increasing the dissolved oxygen content in the water, achieving good oxygenation and promoting water flow effects. It is very effective for increasing dissolved oxygen in water and rescuing fish from surfacing. The water wheel type aerator has good power effects, strong flow mixing effects, and its rotational linear speed is low, which will not harm fish or shrimp. It is suitable for ponds with deep silt and an area of 1000 to 2540m2.

(3) Jet Aerator
The jet aerator has various structural forms, mainly consisting of the main machine, floating body mechanism, support mechanism, and anti-splash mechanism. The main machine is connected to the floating body mechanism via an adjustment rod, which can adjust the jet angle of the main machine to meet the needs of different water depths.

The main working component of the jet aerator is the jet device, also known as the ejector: it relies on high-pressure fluid—water, which, after flowing through the nozzle, forms a high-speed flow—jet, which draws in another low-pressure fluid—air,
and performs energy exchange and material mixing in the device to achieve the purpose of increasing oxygen. The jet pipe of the jet aerator can be adjusted at any angle, which can increase the contact area between air and water. During operation, the propeller-type impeller causes the water body to flow at high speed, creating negative pressure to draw in air, and the air mixes in the water body to form many bubbles, increasing the oxygen content in the water. However, its disadvantage is that the oxygenation efficiency is relatively low, so it is usually used in conjunction with other aerators.
Due to the simplicity of the jet aeration equipment compared to blower machines, its low cost, reliable operation, convenient maintenance, low noise, high power efficiency, and strong versatility, it has also been applied in aquaculture in recent years,
suitable for seedling cultivation, shrimp farming, fish farming, live fish transportation, and oxygenation of water bodies under ice in northern regions.

(4) Spray Aerator
This machine mainly consists of an electric motor, water pump, and floating body. The water pump is generally a submersible pump or axial flow pump, and an umbrella-shaped nozzle is often installed at the water pump outlet to make the water discharge in a film-like form. During operation, the water pump sucks water from the bottom,
and sprays it upwards at high speed through the nozzle, creating a water film and water spray, which expands the contact area between water and air. At the same time, the water film and water spray break into droplets that fall on the water surface, increasing the interface contact. This increases the dissolved oxygen content in the water.
Its characteristics include good mixing of water, as it can draw bottom water to the surface and accelerate vertical water exchange, resembling a fountain. It has good oxygenation capabilities but consumes more power, and can quickly increase the dissolved oxygen content in the surface water while also providing an artistic viewing effect, suitable for use in fish ponds in gardens or tourist areas.

(5) Inflatable Aerator
A machine that pressurizes and disperses air into the bottom layer of water to increase the dissolved oxygen in the water body. This machine performs better in deeper water, making it suitable for use in deep water bodies.

(6) Suction Aerator
The suction aerator sends air into the water through negative pressure suction and mixes it with water to form a vortex that pushes the water forward, due to its strong mixing force. Its oxygenation capability for lower water layers is stronger than that of impeller aerators, while its oxygenation capability for upper water layers is slightly inferior to that of impeller aerators.

(7) Vortex Aerator
This machine is mainly used for oxygenation of water bodies under ice in northern regions, with high oxygenation efficiency.

(8) Oxygen Pump
The oxygen pump is lightweight, easy to operate, and has a single oxygenation function, making it generally suitable for fish seedling cultivation ponds or greenhouse farming pools with a water depth of less than 0.7m and an area of less than 400m2.

(9) New Type of Aerator
With the continuous refinement of fishery demands and the ongoing improvement of aerator technology, many new types of aerators with different functions have emerged.
① Tilling Water Impeller Aerator
This machine mainly consists of a main motor, auxiliary motor, rain cover, gearbox assembly, impeller, floating body blades, circular floating body assembly, support rod, and positioning rod.
It has the dual functions of a tilling water machine and an impeller aerator, capable of stirring the water body, purifying water quality, and quickly increasing the dissolved oxygen in the water.

② Ozone Disinfection Aerator This machine mainly consists of a submersible pump, submersible motor, rain cover, ozone device, air delivery hose, spray nozzle, floating boat, and support.
It has multiple functions including oxygenation, disinfection, sterilization, and water quality conditioning. The use of this machine can reduce the occurrence of fish diseases, save fishermen a lot of medication costs, and prevent secondary pollution, protecting the environment. It is a new type of aquaculture equipment urgently needed in modern aquatic ecological farming.

③ Floating Micro-Pore Aeration Aerator This machine comes in fixed and floating types, with the basic structural principle being the same, mainly consisting of a motor, fan assembly, rain cover, pipeline assembly, hose, aeration pipe, and frame.
The fixed micro-pore aeration aerator has its main pipe placed on the pond bank; the floating micro-pore aeration aerator requires an additional floating boat assembly, with its main pipe placed on the floating boat.

a. The fan assembly consists of a fan, motor, V-belt, and base, which are the main components of the machine. New fans or fans installed after repair should be checked for their rotation direction, which must comply with the direction indicated by the rotation sign; otherwise, the fan
will not exhaust properly. The fan assembly should be powered on for trial operation, and only after confirming normal operation should it be loaded.
b. The pipeline assembly consists of PVC plastic pipes, one-way valves, branch valve switches, and branch joints. Each interface of the pipeline assembly should be sealed with sealing glue or raw tape to prevent air leakage, ensuring the machine operates normally and achieves the effect of pressurizing oxygen.
The one-way valve of the pipeline assembly should be installed on the horizontal main pipeline, and the inner diameter of the pipeline should not be less than the diameter of the fan outlet to ensure airflow. During shutdown, it can prevent gas backflow from damaging the fan and prevent sewage from entering the aeration pipe, causing micro-pores to block, extending the service life of the aeration pipe. During normal operation, all branch valve switches should be fully opened. If a certain aeration disc shows reduced airflow or leaks, the branch valve can be closed, and the problematic aeration disc can be removed for maintenance or replacement without affecting the operation of the entire machine.
The micro-pore aeration disc consists of micro-pore aeration pipes, brackets, and hoses. The micro-pore aeration pipes are fixedly wound on the brackets, allowing the aeration pipes to be adjusted.
The aerator should sink to the bottom of the water, keeping the aeration pipe about 10 cm above the bottom, without contacting the sediment. The hose connects to the aeration pipe, and the other end of the hose connects to the pipeline assembly for aeration. The aeration disc can be collected and moved through the hose.
Micro-pore aeration can effectively increase the dissolved oxygen at the bottom of the water body while effectively promoting the oxidation and decomposition of toxic and harmful substances at the bottom (such as ammonia nitrogen, nitrite, hydrogen sulfide, etc.), improving the bottom environment. This.
The machine is energy-efficient, promotes the safe ecological cycle of fish ponds, and is easy to operate, making it widely used in crab and shrimp ponds.

III. Equipment of Aerators
1. Principles of Aerator Equipment

The selection principle of aerators is to fully meet the oxygen demand for the normal growth of fish, effectively prevent hypoxia and fish deaths, reduce feed utilization and fish growth rates, and prevent the occurrence of fish diseases, while also minimizing operating costs and saving expenses. Therefore, the selection of aerators should comprehensively consider factors such as pond depth, different fish pond areas, aquaculture yield, aerator efficiency, and operating costs.
2. Equipment of Aerators
(1) Determine the loading capacity of the aerator.

Determining the loading capacity generally considers water depth, area, and pond shape. Rectangular ponds are best suited for water wheel types, while square or circular ponds are better for impeller types; each kilowatt of impeller aerator power can basically meet the oxygen needs of 3.8 mu (about 2530 m2) of fish ponds.
For fish ponds with a surface area of 4.5 mu (about 3000 m2) or more, it is advisable to consider equipping more than two aerators.
(2) Installation location of the aerator.

The aerator should be installed in the center of the pond or slightly upwind. Generally, it should be more than 5 m away from the pond dam and fixed with stakes or anchors. When installing the impeller aerator, ensure that the water flow generated during operation does not stir up the sediment at the bottom of the pond.
Additionally, pay attention to electrical safety during installation, implement safety protection measures, and conduct regular inspections and maintenance.
3. Principles of Aerator Use

The use of aerators should be scientifically determined based on the changes in dissolved oxygen in the water and the function of the aerator, establishing the operating time and duration. It is essential to adhere to the principle of operating during sunny midday, early morning on cloudy days, midnight during continuous rain, and not operating in the evening; the operating time should be determined based on weather, water quality, the floating situation of fish and shrimp, and the loading area of the aerator.
For ponds without aeration facilities, some oxygenation agents should be equipped for emergency use.
IV. Safety Operation Precautions for Aerators
(1) The aerator uses 380V three-phase AC power, and the power supply must use a dedicated circuit, with electrical connections made by professional electricians according to electrical safety operation procedures.

(2) The motor must be equipped with leakage, phase loss, and undervoltage protection devices to ensure the circuit operates normally.

(3) The power supply line should use a three-phase four-wire copper core rubber cable, with a recommended wire diameter of 4x2.5mm2, ensuring secure connections and reliable grounding.

(4) The input power supply voltage is 380V, with voltage fluctuations not exceeding ±5% of the rated voltage to prevent undervoltage, which can damage the motor during long-term use.

(5) It is strictly prohibited to use metal wires such as iron wire to connect and fix the aerator.

(6) When maintaining, servicing, moving the aerator, or disassembling the motor, the power supply must be cut off first to ensure personal safety.

(7) When the aerator is in operation, no one is allowed to enter the fish pond to prevent electric shock and mechanical accidents.