Applicability evaluation of the PID controlled water pump for flow-through aquaculture systems considering tidal variations

• Affinity Law-based pump model to evaluate PID control for flow-through aquaculture. • Developed a flow rate model considering tidal variations. • P and PD controls reduce flow deviation and have low energy usage variability. • PI and PID controls overreact, causing extreme flow variability and energy usage. Flow-through aquaculture systems support high-density farming but are highly sensitive to tidal variations, resulting in flow instability and energy inefficiency—yet their control dynamics remain largely unexplored. To address this gap, this study developed an Affinity Law-based pump performance model using measured data on pump flow rate, power consumption, and tidal levels, and conducted a comparative analysis of classical PID control structures to quantitatively evaluate the fundamental control characteristics of the system. The results demonstrated that the P and PD controls exhibited relatively stable flow regulation, with the PD control showing the lowest flow rate standard deviation (5.21–38.64 m 3 /h) and overshoot (13.87–125.97 m 3 /h) across different control intervals. In contrast, the PI and PID controls exhibited significantly greater flow variability, with standard deviations in the range of 247.57–282.52 m 3 /h and overshoot values up to 299.72 m 3 /h, consistently observed regardless of the interval length. The P and PD controls also exhibited stable daily energy consumption patterns, with standard deviation values ranging from 2.8 to 6.04 kW, while the PI and PID controls showed increasingly unstable behavior, with deviations reaching up to 30.33 kW. This study highlights the potential of improving pump control strategies by addressing the flow variability caused by tidal changes and provides a technical foundation for enhancing the sustainability of flow-through aquaculture systems.