In traditional impressions, aquaculture is often associated with "relying on the weather" and "empiricism". Masters judge the quality of water by observing the color of the water, weather, and the behavior of the livestock. This is not only labor-intensive, but also like a gamble - a sudden deterioration of water quality can lead to the complete annihilation of the army and cause huge economic losses.

However, a silent revolution driven by the Internet of Things (IoT) and intelligent sensing technology is happening in ponds, cages, and recirculating aquaculture systems (RAS) around the world. Water quality sensors are the core of this revolution, fundamentally changing the mode of aquaculture and elevating it to an efficient, accurate, and safe modern industry.

1、 Why is water quality so critical?

Before delving into sensors, we first need to understand that water is to aquatic organisms what air is to us. The water quality parameters directly determine the survival, health, and production efficiency of aquaculture products. Several core indicators include:

• Dissolved oxygen (DO): the foundation of life. Hypoxia can lead to slow growth, stress, and even widespread death.

• PH value (acidity or alkalinity): It affects the metabolism and immunity of aquaculture products, and extreme pH values are toxic.

• Temperature: directly affects metabolic rate, food intake, and growth rate.

• Ammonia nitrogen (NH ∝ - N): Produced by the decomposition of livestock excrement, it is highly toxic and is the main stressor that induces diseases.

• Nitrite (NO ₂ - N): an intermediate product of ammonia nitrogen conversion, also highly toxic.

The traditional manual detection method usually only measures 1-2 times a day and cannot capture the dynamic changes in water quality, especially during the dangerous period with the lowest dissolved oxygen at night, making it difficult for management personnel to continuously monitor.

2、 Water quality sensor: the "digital sensory" of breeders

Water quality sensors are like "underwater sentinels" that work tirelessly 24/7, continuously converting chemical and physical signals in the water into precise digital data. These sensors are deployed in the water body and transmit data in real-time to the central control platform or the breeders' mobile app through wired or wireless means.

Common types of sensors include:

• Optical dissolved oxygen sensor: Based on the principle of fluorescence quenching, it is more stable and requires less maintenance than traditional electrode methods.

• PH/ORP sensor: uses glass electrodes to continuously monitor the acidity and redox potential of water bodies.

• Ammonia nitrogen/ion selective electrode (ISE) sensor: directly monitors the concentration of toxic non ionized ammonia.

• Multi parameter water quality monitoring instrument: one probe integrated with temperature pH、DO、 Various functions such as conductivity.

3、 How to improve the efficiency and safety of aquaculture?

1. From "experience farming" to "precision farming", greatly improving efficiency

• Accurate feeding: Based on real-time dissolved oxygen and water temperature data, the optimal feeding time for aquaculture can be determined. For example, increasing the feeding amount when dissolved oxygen is sufficient, and reducing or even stopping feeding when dissolved oxygen is low, to avoid feed waste and water pollution. According to statistics, this can save 10% -20% of feed costs.

• Optimizing growth environment: The system can automatically record the water temperature change curve, allowing breeders to choose the season that is most suitable for the growth of breeding varieties, or create the best environment by adjusting water depth and other measures, significantly shortening the breeding cycle.

• Reduce labor costs: There is no need for technicians to frequently conduct manual measurements at each pond mouth. One person can monitor large breeding areas through mobile phones or computers, greatly reducing labor intensity and labor costs.

2. Build an intelligent system of "warning regulation" to comprehensively ensure safety

• 7x24 hour risk warning: The system can set safety thresholds for key indicators such as dissolved oxygen and ammonia nitrogen. Once the data is abnormal, it will be immediately alerted through SMS, APP push, sound and light, etc., so that breeders can take intervention measures hours or even tens of hours before the accident occurs, turning passive remedies into active warnings.

• Intelligent linkage control: The most advanced system can already achieve automatic control. When the dissolved oxygen is lower than the set value, the system will automatically turn on the aerator; When the pH value deviates from the range, the dosing system can be automatically activated. This kind of immediate response is something that humans cannot achieve and can effectively avoid major accidents such as nighttime hypoxia.

• Traceability and decision support: All historical data is fully recorded, forming a 'breeding log'. If there is a problem, it can be traced back to analyze the trajectory of water quality changes and quickly locate the cause. Meanwhile, big data analysis can help optimize breeding strategies and provide scientific basis for future production plans.

• Ensuring product safety and sustainability: Good water quality means reducing the occurrence of diseases, thereby reducing the use of antibiotics and chemical drugs, and ensuring the quality and safety of aquatic products from the source. At the same time, precise feeding and medication also reduce pollution to the surrounding environment, making aquaculture more environmentally friendly and sustainable.

4、 Future Trends and Challenges

In the future, water quality sensing technology will develop towards greater precision, durability, and lower cost. The combination with artificial intelligence (AI) will be the next trend - AI models can not only provide early warning, but also predict the trend of water quality changes in the future by analyzing historical data and real-time information, truly achieving intelligent management.

Of course, challenges still exist, such as the problem of long-term biological pollution (scaling) of sensors underwater, and the threshold for initial investment costs for small and medium-sized farmers. But with the popularization of technology and the decrease in cost, water quality sensors will inevitably become a standard configuration for every modern breeder, just like smartphones.

Conclusion

The water quality sensor may seem like a simple data collection device, but it is a key bridge connecting traditional aquaculture and smart agriculture. It endows breeders with the ability to perceive the underwater world, transforming the breeding process from a vague "art" to a clear "science". Embracing this new trend is not only a business decision to enhance profitability, but also a necessary path towards responsible, sustainable, and safe modern aquaculture.