<![CDATA[Nutrient management in modern hydroponic systems requires a high degree of precision to optimize plant growth. Controlling nutrient concentration levels in parts per million (PPM)—whether manually or using conventional on/off systems—is often inefficient and prone to causing overshoot. This study aims to design and build a prototype of an automated nutrient dosing system using an ESP32 microcontroller equipped with an adaptive Proportional-Integral-Derivative (PID) control algorithm and integrated with Internet of Things (IoT) technology. The system uses a Total Dissolved Solids (TDS) sensor to measure solution concentration, a DS18B20 temperature sensor for water temperature compensation, and three DC peristaltic pump actuators controlled via an L298N driver module using PWM signals. A heuristic gain scheduling (auto-tuning) algorithm was implemented so that the PID parameters could dynamically adjust their values based on the magnitude of the actual error. Test results showed that the adaptive PID method was able to respond quickly and settle stably without excessive overshoot. In a rise test with a setpoint of 400 PPM, the system achieved a rise time of 215.6 seconds with minimal overshoot of 0.20% and a steady-state error of 5.07 PPM. This system also proved resilient in handling sudden external disturbances in the form of added distilled water, with a recovery time of 96.5 seconds and a maximum overshoot of 5.00%. The integration of IoT infrastructure via the Blynk platform, automatic logging to Google Spreadsheets, and the presence of a Local Web Server successfully enabled users to monitor operations in real-time from a distance. It can be concluded that the design of this device effectively addresses the weaknesses of static control systems and provides high operational efficiency in hydroponic cultivation.]]>
