Electrical conductivity and pH adjusting system for hydroponics by using linear regression

The purposes of this study were to implement the automatic control EC and pH system in reservoir. The automatic control system operate when get signal output from micro-controller. For micro-controller implement EC and pH adjusting equation that were applied from linear regression. The reason to use linear regression because of in experiment amount of A&B solution or nitric acid that adding to reservoir effect to increasing number of EC or pH in the same direction. For EC and pH adjusting equation use 3 variables are target (output), EC or pH measurement (input), and amount of A&B solution or Nitric acid (control process). Micro-controller compute EC and pH adjusting equation to find amount of A&B solution or Nitric acid that need to fill in reservoir for control EC and pH in range of target. The results of experiment show the system that using EC adjusting equation can control EC accuracy more than 80.8% from experiment. And the pH adjusting equation can control pH accuracy more than 95% from experiment.