Experimental Assessment of Control Loop Performance: A Methodology for Comparing On-Off and PID Actions in Dissolved Oxygen Regulation

Experimental validation of dissolved oxygen (DO) control in aquaculture is often limited by biological variability, environmental factors, and pond hydrodynamics, which reduce reproducibility and hinder reliable assessment. To address this, we developed a laboratory-scale, control-oriented platform that minimizes external disturbances and enhances statistical reliability. Oxygen demand was emulated via chemical deoxygenation with sodium sulfite, so aeration experiments begin from near‑zero dissolved oxygen (DO). Sodium sulfite is added only during initialization; any residual persists briefly into the early closed-loop phase. Using this framework, On-Off control with hysteresis and discrete-time PID control were compared in terms of overshoot, rise time, settling time, and steady-state error. Under a confidence criterion, the PID controller required fewer repetitions than the On-Off strategy to achieve comparable reliability.