Water quality deterioration is the core factor restricting the survival rate and yield of modern intensive aquaculture. Traditional aeration equipment relies on manual timing switching or single dissolved oxygen (DO) monitoring, which fails to respond synergistically to changes in oxidation-reduction potential (ORP) and ammonia-nitrogen concentration, resulting in excessive energy consumption, insufficient oxygen supply or accumulation of toxic harmful substances in aquaculture water. To solve the above pain points, this study develops a dedicated aquaculture water quality analyzer equipped with an integrated automatic aeration control system. The system collects real-time water quality data of dissolved oxygen, ORP and ammonia nitrogen through high-precision digital sensors, adopts a multi-parameter collaborative fuzzy control algorithm, and realizes automatic start-stop and stepless speed regulation of aeration equipment. Field experimental results show that compared with conventional single DO aeration control equipment, this integrated control system can stabilize pond water quality within the optimal breeding threshold all day long, reduce aeration energy consumption by 18.7%, control ammonia nitrogen concentration below 0.2 mg/L stably, and improve the survival rate of cultured aquatic products by 7.2%. The designed water quality analyzer and matched aeration control system have the advantages of low cost, strong anti-interference performance and easy deployment, which is suitable for large-scale promotion in freshwater and seawater intensive aquaculture ponds.
1. Introduction
With the rapid upgrading of global aquaculture industry towards intensification, high-density and industrialization, the self-purification capacity of aquaculture water bodies decreases sharply, and water quality fluctuation becomes the primary threat to healthy breeding. Among all water quality indicators, dissolved oxygen is the most basic environmental factor affecting the respiration and growth of fish, shrimp and crabs. Long-term low dissolved oxygen will lead to hypoxia stress and mass death of aquatic organisms. ORP reflects the redox state of water body, which can characterize the decomposition degree of residual bait, feces and organic pollutants in water. Ammonia nitrogen is a typical toxic inorganic pollutant in aquaculture water; excessive ammonia nitrogen will damage the gill tissue of aquatic organisms, reduce immunity and induce frequent outbreaks of bacterial diseases.
At present, most intelligent aeration systems on the market only take dissolved oxygen as the single control basis. This single monitoring mode has obvious defects: even if the dissolved oxygen content meets the standard, high ammonia nitrogen and low ORP caused by organic pollution still cannot be eliminated by aeration regulation alone, and hidden water quality risks still exist. Some existing multi-parameter water quality monitoring devices only support data display and alarm functions, without linkage automatic aeration control logic, which still requires manual operation by farmers and cannot realize unattended intelligent breeding management.
In view of the above technical deficiencies, this paper designs a specialized integrated water quality analyzer for aquaculture. Different from traditional single-index control equipment, this system fuses three core water quality parameters: dissolved oxygen, ORP and ammonia nitrogen, constructs a multi-dimensional aeration decision-making model, and realizes full-automatic closed-loop control of aeration volume. This research aims to optimize water quality regulation efficiency, cut breeding power cost, reduce water quality pollution risks, and provide reliable technical equipment support for intelligent and energy-saving aquaculture.
2. Overall System Design
2.1 System Overall Architecture
The proposed aquaculture dedicated water quality analyzer and integrated aeration automatic control system is divided into four core modules: multi-parameter sensor acquisition module, data processing and analysis module, intelligent control execution module and human-computer interaction and remote transmission module. The overall working logic is as follows: first, underwater sensors synchronously collect real-time values of dissolved oxygen, ORP and ammonia nitrogen in aquaculture water; then the main control chip filters and calibrates the original collected data to eliminate interference signals such as water flow fluctuation and sensor attachment dirt; afterwards, the system matches the real-time water quality data with the preset optimal breeding threshold, generates aeration adjustment instructions through the built-in collaborative control algorithm; finally, the control module drives aerators to adjust operating power or realize automatic start and stop. The system supports local screen real-time data viewing, local parameter modification, and remote mobile terminal data push, meeting both on-site and remote monitoring demands of farmers.
2.2 Selection of Core Monitoring Sensors
To adapt to the complex underwater environment of aquaculture ponds with high turbidity and many impurities, all sensors adopt waterproof, anti-fouling and corrosion-resistant probes, and are equipped with automatic cleaning structures to reduce measurement errors caused by dirt attachment. The key technical parameters of sensors are shown in Table 1.
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Monitoring Parameter
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Measurement Range
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Measurement Accuracy
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Response Time
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|---|---|---|---|
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Dissolved Oxygen (DO)
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0-20 mg/L
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±0.1 mg/L
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≤10 s
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|
ORP
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-2000mV ~ +2000mV
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±5 mV
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≤15 s
|
|
Ammonia-Nitrogen
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0-5 mg/L
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±0.05 mg/L
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≤30 s
|
Table 1 Core technical parameters of water quality sensors
2.3 Optimal Water Quality Threshold for Aquaculture
Combined with national aquaculture water quality standards and actual breeding experience of mainstream freshwater fish and shrimp, the system sets unified optimal control thresholds and alarm thresholds for three parameters, as shown below:
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Dissolved Oxygen: optimal range ≥5 mg/L; aerator automatically starts when DO <4.5 mg/L; high-power aeration mode is activated when DO <3 mg/L
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ORP: optimal range 200mV-400mV; aeration enhancement is triggered when ORP <200mV to accelerate organic matter oxidation and improve water redox environment
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Ammonia-Nitrogen: optimal range ≤0.2 mg/L; forced aeration runs continuously when ammonia nitrogen >0.5 mg/L to promote nitrification reaction and degrade toxic ammonia nitrogen substances
3. Multi-Parameter Collaborative Aeration Control Logic
Different from the traditional single DO threshold on-off control, this system adopts a fuzzy collaborative control strategy based on three parameters, which avoids frequent start and stop of aerators caused by instantaneous fluctuation of single water quality index. The control logic is divided into three working modes to adapt to different water quality conditions of ponds:
3.1 Normal Operation Mode
When all three parameters are within the optimal threshold range, the system keeps the aerator running at low power intermittently. It only maintains slight water body convection to prevent water stratification, which minimizes energy consumption while keeping water quality stable.
3.2 Single Parameter Abnormality Mode
When only one index exceeds the standard, the system executes targeted aeration adjustment: low DO triggers conventional oxygenation; low ORP enhances aeration intensity to accelerate organic pollutant decomposition; excessive ammonia nitrogen prolongs aeration duration to boost microbial nitrification. The system will not blindly increase power to avoid unnecessary energy waste.
3.3 Dual or Triple Parameters Abnormality Mode
When two or three indicators are out of standard simultaneously, it indicates severe deterioration of pond water quality. The system immediately starts full-power continuous aeration, pushes remote alarm information to farmers, and accelerates water quality recovery through maximum aeration efficiency until all parameters return to the normal optimal range.
4. Field Experiment and Result Analysis
4.1 Experimental Scheme
To verify the practical application effect of the designed system, this study selects two identical commercial freshwater shrimp culture ponds with an area of 1.5 mu each for a 60-day comparative field experiment. The control group adopts the traditional automatic aeration system only based on dissolved oxygen monitoring; the experimental group adopts the aquaculture specialized water quality analyzer and multi-parameter collaborative aeration control system designed in this paper. The water quality data, daily aeration power consumption and shrimp survival rate of the two groups are recorded synchronously every day during the experiment.
4.2 Experimental Results and Analysis
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Water quality stability comparison: The control group had frequent fluctuation of ORP and ammonia nitrogen. Even if dissolved oxygen was qualified, ammonia nitrogen concentration often exceeded 0.3 mg/L, and the minimum ORP dropped to 156mV. The experimental group maintained dissolved oxygen above 5.0 mg/L, ORP stably between 210mV-380mV, and ammonia nitrogen always below 0.2 mg/L, realizing full-range stable control of water quality.
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Energy consumption comparison: The total aeration power consumption of the control group in 60 days was 286.4 kWh, while that of the experimental group was 232.7 kWh. The integrated collaborative control system reduced overall energy consumption by 18.7%, realizing significant energy-saving effect.
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Breeding benefit comparison: The survival rate of shrimp in the control group was 82.1%, while that in the experimental group reached 89.3%. Benefiting from stable water quality and reduced toxic stress, the growth rate of shrimp in the experimental group was also improved correspondingly.
5. Discussion
The experimental results fully prove that multi-parameter collaborative aeration control is obviously superior to traditional single dissolved oxygen control mode. Aeration not only increases dissolved oxygen content in water, but also promotes water circulation, strengthens the oxidation decomposition of organic pollutants, and accelerates the nitrification process of ammonia nitrogen. Therefore, taking DO, ORP and ammonia nitrogen as joint control indicators can accurately reflect the overall health status of aquaculture water body, rather than judging water quality only relying on single oxygen content.
In practical breeding scenarios, sudden weather changes such as rainy days and high temperature will accelerate water quality deterioration. The system can quickly respond to composite water quality changes through multi-index fusion judgment, which makes aeration control more scientific and reasonable. In addition, the integrated design of water quality analyzer and control host simplifies on-site wiring and equipment installation, which is more friendly to small and medium-sized aquaculture farmers with limited professional operation ability.
There are still limitations in this research: the current system does not integrate water temperature and pH monitoring indicators, and the algorithm can be further optimized for extreme low-temperature and high-temperature breeding environments. Subsequent research will add more auxiliary water quality indicators and adopt machine learning algorithms to realize predictive aeration control, further improving the intelligence level of the system.
6. Conclusion
Aiming at the defects of single-index aeration control and separated monitoring and control equipment in existing aquaculture water quality management equipment, this paper develops a specialized aquaculture water quality analyzer integrated with automatic aeration control system based on dissolved oxygen, ORP and ammonia nitrogen levels. The system realizes real-time synchronous collection of three core water quality parameters and intelligent linkage regulation of aeration equipment through fuzzy collaborative control algorithm. Field experiments verify that the system can effectively stabilize comprehensive water quality indicators of aquaculture ponds, reduce aeration energy consumption, improve aquatic product survival rate, and reduce breeding risks caused by water quality mutation. With advantages of low equipment cost, simple installation, stable operation and unattended automatic control, this device has broad application prospects in modern intelligent intensive aquaculture industry.
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