Lush green lettuce thrives in nutrient solution within cultivation tanks, all controlled by several quietly working water quality sensors.
In a university laboratory in Jiangsu Province, a batch of lettuce is growing vigorously without soil, thanks to a hydroponic smart monitoring system based on narrow-band IoT technology. Researcher Zhang Jing explained that the system uses multiple water quality sensors to monitor nutrient solution parameters in real-time, combined with fuzzy control methods to automatically adjust water quality according to crop needs.
As hydroponic technology becomes more widespread, these inconspicuous water quality sensors are playing an increasingly important role. From professional research institutions to ordinary households, smart hydroponic systems are quietly transforming traditional farming methods.
01 Current State of Hydroponic Technology
Compared to traditional soil cultivation, hydroponics enables faster crop growth and reduces pest problems. Since crops continuously absorb nutrients from the nutrient solution, it’s essential to monitor the water quality parameters of the hydroponic nutrient solution promptly and accurately, and replenish nutrients as needed.
In recent years, with the development of sensor technology and cost reduction, smart hydroponic systems have begun moving from research institutions to ordinary households.
A typical smart hydroponic system usually consists of three main components: sensors, controllers, and actuators.
Among these, sensors are responsible for collecting various water quality parameters, serving as the “eyes” and “ears” of the system. Their accuracy and stability directly determine the success or failure of the entire hydroponic system.
02 Detailed Overview of Core Sensors
pH Sensors
pH value is crucial for crop growth in hydroponics. As anyone in aquaculture knows, the optimal pH range for water bodies is between 7.5-8.5.
pH water quality sensors detect hydrogen ion concentration in measured substances and convert it into corresponding usable output signals.
H+ ions in the solution interact with the sensor’s electrode to produce a voltage signal, and the voltage magnitude is proportional to the H+ concentration. By measuring the voltage signal, the corresponding pH value of the solution can be obtained.
Specialized pH sensors designed for hydroponic applications are commercially available, such as automatic hydroponic pH sensors supporting standard communication protocols, with measurement ranges of 0-14.00 pH and resolution up to 0.01 pH, enabling precise monitoring and control.
Dissolved Oxygen Sensors
Dissolved oxygen is a key factor for healthy root growth in hydroponic crops. Water bodies not polluted by oxygen-consuming substances maintain dissolved oxygen at saturation levels.
Dissolved oxygen sensors measure the amount of oxygen dissolved in water.
Oxygen molecules from the measured solution permeate through the sensor’s selective membrane and undergo corresponding reduction or oxidation reactions at the internal cathode and anode, simultaneously generating current signals. The current magnitude is proportional to the dissolved oxygen concentration.
Professional dissolved oxygen sensors are available in different designs: some capable of withstanding harsh environmental conditions while providing excellent accuracy; others optimized for response time, suitable for spot checking and analytical applications.
Ion Concentration Sensors
Ion concentration sensors are crucial equipment for monitoring nutrient solution composition. The concentrations of specific ions such as nitrate, ammonium, and chloride directly affect crop growth.
For example, specialized ammonium ion sensors can measure ammonium content in natural waters, surface water, groundwater, and various agricultural applications.
A patent for a hydroponic solution ion concentration sensor from an agricultural university integrates ion electrodes, temperature sensors, and pH sensors, enabling quick understanding of ion concentration changes, temperature variations, and pH changes in hydroponic solutions.
Electrical Conductivity (EC) Sensors
Electrical conductivity is a key indicator measuring the total ion concentration in nutrient solution, directly reflecting the fertility level of the nutrient solution.
Automatic EC transmitters specifically designed for agricultural irrigation and hydroponics offer measurement ranges up to 0-4000 µS/cm, supporting standard output protocols, capable of connecting to dosing pumps/valves and controlling pump/valve switches.
Temperature and Turbidity Sensors
Temperature affects crop root growth and metabolic activity, while turbidity reflects the amount of suspended particles in the nutrient solution.
In smart greenhouse hydroponic tank projects, developers can use high-precision digital temperature and humidity sensor modules, with typical temperature accuracy of ±0.3℃ and resolution of 0.01℃.
Specialized turbidity sensors can be used with multi-parameter instruments to monitor the turbidity level of nutrient solutions.
03 Integrated Applications in Smart Systems
Data from individual sensors is often insufficient to comprehensively reflect the complete hydroponic environment, making multi-sensor fusion a growing trend in smart hydroponic systems.
Multi-parameter probes with cost-effective designs can be easily integrated with control systems and telemetry systems, suitable for long-term deployment.
Research teams have developed IoT-based smart monitoring systems for hydroponics that use mobile application interfaces for real-time monitoring of hydroponic environmental parameters, combined with intelligent control methods to adjust nutrient solution water quality parameters based on operational experience and crop needs.
Test results show that when such systems regulate nutrient solutions, key parameters like pH and electrical conductivity can maintain stable preset values within reasonable timeframes.
04 Technical Challenges and Future Trends
Although hydroponic sensor technology has made significant progress, several challenges remain. Long-term stability, anti-fouling capability, and calibration frequency of sensors are major issues in practical applications.
Particularly ion-selective electrodes are susceptible to interference from other ions and require regular calibration.
Future hydroponic sensors will develop toward multifunctionality, intelligence, and cost reduction.
Advanced sensor systems already enable high-performance measurement of various parameters, including chlorophyll, pigments, fluorescence, turbidity, and more.
Meanwhile, with the development of open-source projects, the barriers to entry for smart hydroponic systems are lowering, enabling more people to participate in this agricultural transformation.
Today, more and more urban residents are beginning to experiment with home hydroponics. On residential balconies in various cities, leafy greens grow vigorously in smart hydroponic tanks based on popular microcontroller platforms.
“Water quality sensors are the core of hydroponic systems—they’re like the ‘taste buds’ of plants, telling us which nutrients need adjustment,” described an enthusiast.
Continuous breakthroughs in sensor technology are turning precision agriculture from an ideal into reality.
We can also provide a variety of solutions for
1. Handheld meter for multi-parameter water quality
2. Floating Buoy system for multi-parameter water quality
3. Automatic cleaning brush for multi-parameter water sensor
4. Complete set of servers and software wireless module, supports RS485 GPRS /4g/WIFI/LORA/LORAWAN
For more water sensor information,
please contact Honde Technology Co., LTD.
Email: info@hondetech.com
Company website: www.hondetechco.com
Tel: +86-15210548582
Post time: Nov-07-2025