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Do you really understand the “three on, two off” rule for aerators?

“Three On” refers to turning on the aerator at noon on sunny days, in the early morning of the following day on cloudy days, and in the middle of the night during prolonged rainy periods. “Two Off” means not turning on the aerator in the evening and not turning it on at noon on rainy days. Three On 1. Turn on the aerator at noon on sunny days During hot summer and autumn days, the water-churning action of the aerator can break the uneven vertical distribution of dissolved oxygen in the pond, promoting convection between the upper and lower layers of water. This stirs the large amount of supersaturated oxygen produced by photosynthesis in the upper-layer phytoplankton down to the bottom layer, accelerating the decomposition of organic matter at the bottom and thus reducing or preventing fish from floating head-up early the next morning. Generally, it’s best to run the aerator for one to three hours around noon. 2. Turn on the aerator in the early morning of the following day on cloudy days On cloudy days, the light intensity in the upper layer of the pond is weak, resulting in less oxygen production by phytoplankton and lower dissolved oxygen levels in the water. Meanwhile, oxygen-consuming factors tend to increase. By early morning, the supply of dissolved oxygen becomes insufficient. At this time, turning on the aerator can fully utilize its aeration and oxygen-increasing functions, speeding up the release of oxygen-consuming gases in the water and directly increasing oxygen levels, thereby avoiding low peaks in dissolved oxygen. The ideal running time is about three to five hours in the early morning, usually until sunrise. 3. Turn on the aerator in the middle of the night during prolonged rainy periods During prolonged rainy weather, not only is photosynthesis by phytoplankton weak, but also wind speed is low, atmospheric pressure is reduced, and oxygen consumption increases significantly. As a result, fish often start floating head-up in the middle of the night. Turning on the aerator in the middle of the night can increase dissolved oxygen and relieve the phenomenon of fish floating head-up. Once turned on, the aerator should keep running continuously until sunrise. Additionally, if the water is rich in nutrients and there are many fish, causing severe floating head-up, the aerator should be turned on earlier, before the fish actually start floating, to prevent the occurrence of mass fish deaths due to "pond overflow." Two Off 1. Do not turn on the aerator in the evening In the evening, the dissolved oxygen level in the pond is usually not yet critical, so there’s generally no need to turn on the aerator. If you do turn it on in the evening, not only will its effect be minimal, but it may also cause premature convection between the upper and lower layers of the pond, leading to earlier vertical mixing and increasing the oxygen-consuming water layer, thus creating an oxygen debt. By dawn, the dissolved oxygen level could reach its lowest point, easily triggering fish to float head-up. Therefore, it’s best not to turn on the aerator in the evening. 2. Do not turn on the aerator at noon on rainy days Because of insufficient sunlight on rainy days, thermal stratification in the pond is not obvious, and photosynthesis by phytoplankton is weaker, so the dissolved oxygen level in the surface layer is not even supersaturated. In such conditions, turning on the aerator not only fails to increase dissolved oxygen in the lower layer but also reduces the oxygen-producing capacity of phytoplankton in the upper layer, further increasing the oxygen-consuming water layer and accelerating oxygen depletion in the lower layer, which easily triggers fish to float head-up. Thus, turning on the aerator at noon to stir the water makes no sense. This is the traditional “three on, two off” approach, and the basis for judgment is precisely the daily variation pattern of dissolved oxygen levels in still ponds, used to control the starting and stopping of the aerator. But how do we determine whether the dissolved oxygen level in the water is high or low? In the past, farmers relied solely on their own aquaculture experience—there was no scientific basis for deciding when to turn on the aerator, how many aerators to use, or how long to run them. As a result, it was impossible to confirm whether the dissolved oxygen level in the water was truly sufficient. Moreover, in order to ensure “sufficient” oxygen, farmers often kept the aerators running for extended periods, unknowingly driving up electricity costs. However, I believe that as stocking densities continue to rise, aerators increasingly serve more as water-churning devices. Beyond the “three on, two off” rule, it’s important to pay attention to the operating time of aerators during hot weather: longer running times enhance the exchange between upper and lower water layers, helping to cool the water and stimulate feeding; during cooler weather, shorter running times are sufficient. Running the aerator longer at midnight and shorter at noon; running it longer when winds are light and shorter when winds are strong; running it longer when the pond receives heavy fertilization and shorter when fertilization is light.

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The first National Aquaculture Mechanization Field Conference was held in Changzhou.

The surge-wave aerator floats on the shimmering water surface like a lifebuoy, while the propeller-type variable-frequency oxygenator creates tiny fountains with its splashing water... This scene, resembling a “water park,” unfolded at the observation site of the first National Aquaculture Mechanization Field Conference. Hosted by the Agricultural Mechanization Administration of the Ministry of Agriculture and Rural Affairs, the conference was recently held in Jintan District, Changzhou City, Jiangsu Province. Over 200 participants attended, including Wang Jiayun, Deputy Director of the Agricultural Mechanization Administration of the Ministry of Agriculture and Rural Affairs, heads of relevant departments, experts and scholars, and representatives from enterprises. The event attracted nearly 40 companies from across the country, showcasing more than 120 types of aquaculture machinery and equipment—the largest number of participating enterprises and products ever featured at a field conference in recent years. On that day, attendees visited an intelligent fish farm located in Zhizhen Town, Jintan District. “The core area of the intelligent fish farm covers 6,500 mu and has a total investment of 500 million yuan. It is the core zone for Jintan District’s efforts to establish a National Agricultural Science and Technology Park and a Jiangsu Provincial Agricultural High-tech Zone, and was included in Jiangsu Province’s major projects for 2020,” said Zhang Jinbiao, Deputy Mayor of Zhizhen Town, Jintan District. A range of advanced machinery—including automatic feeders, aerial broadcasting loudspeakers, automatic mowers, automatic oxygenators, automated water intake and drainage systems, and online water-quality monitoring devices—have already been put into use at this fish farm, enabling mechanization and intelligent operation of key stages in river crab farming. Jintan is known as the “Hometown of Chinese Mitten Crabs,” and river crabs are the district’s first single-product industry to exceed 1.5 billion yuan in output value. However, today, labor shortages and rising labor costs have become major challenges hindering the development of the river crab industry. By taking the lead nationwide in building intelligent fish farms, Jintan District is making a valuable exploration toward accelerating the mechanization of river crab production.

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The “Tech-Driven” Approach to Marine Aquaculture on Islands

This aquaculture base is located in the Shengsi Islands. Situated in the East China Sea, the Shengsi Islands are a magical archipelago shaped by nature itself. Today, they serve as a renowned scenic area among China’s island groups and are also a major production hub for key economic fish species, earning them the well-deserved title of “Natural Fish Treasury.” The nickname “Natural Fish Treasury” naturally owes much to the region’s superb natural environment. Yet the thriving development of aquaculture in Shengsi is also inseparable from the support of advanced technology. The adoption of modern aquaculture practices has made this aquaculture operation thoroughly high-tech. At this large yellow croaker aquaculture base, there are 10 fish ponds. In June of this year, the head of the base released hundreds of thousands of yellow croaker and small yellow croaker fry into the ponds. Let’s take a closer look at just what kind of technological elements are involved here.

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2020

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Newcomers to the aquaculture industry need to be cautious—next year’s aquaculture market conditions could be about to change!

Over the past two years, crawfish farming has been nothing short of booming—so hot that it’s practically exploding. Everywhere you look, people are scrambling to find land for raising crawfish; to outsiders, it seems as though they’re not even looking for land—they’re just chasing money. As a result, land rental prices have been climbing steadily. In many key crawfish-farming regions, land rents have soared beyond 1,000 yuan per mu, and in some cases even higher. These skyrocketing costs have significantly increased both the upfront investment and the risks associated with later-stage farming. Right now, whether it’s those working away from home or successful entrepreneurs with some capital, everyone wants to return to their hometowns and dive into the crawfish farming business, eager to grab a piece of the action. But is the reality really as rosy as they imagine? Can raising crawfish really bring in big money—and fast? Unfortunately, many people may be in for a rude awakening. The enormous initial capital investment, the long payback period, coupled with the need for specialized farming techniques, experience, effective management, and the ability to withstand substantial farming risks—all these factors mean that most newcomers end up losing their entire investment.

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2020

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The Function and Usage of Fish Pond Aerators

In rural areas, virtually every village has several fish ponds. In recent years, many people have returned to their hometowns to start businesses and engage in aquaculture, so these fish ponds have found new uses. In any fish pond where fish are raised, you’ll often see a machine installed—this machine is an oxygenator. So, what’s the purpose of installing an oxygenator in a fish pond? Why do we sometimes turn the oxygenator on, and other times leave it off for long periods? And when is it most effective to run the oxygenator? Today, let’s talk about this topic.

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2020

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Introduction to the Use of Fish Pond Aerators

Aerator supplier: The application of pond aerators in fish ponds is an important measure for increasing dissolved oxygen levels in the water, preventing fish from floating to the surface, and boosting aquaculture yields.

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2021

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