pH Dosing Controller image

pH Dosing Controller

Project Overview

Built an automated pH monitoring and dosing system using a Raspberry Pi 4, Atlas Scientific EZO-pH sensor, and dual EZO-PMP peristaltic pumps to hold a liquid at a target pH setpoint.

Skills Used

Raspberry Pi Python Flask REST APIs I2C / Hardware Drivers Control Systems Atlas Scientific EZO Sensors Tailscale VPN / Remote Access

pH Dosing Controller

Repo: Ahmedmoui/ph-controller

Overview

An automated pH control system that continuously monitors the pH of a liquid and doses acid or base as needed to hold it at a target setpoint, instead of relying on manual titration.

Impact

This controller enables more complex and tightly controlled experiments in the civil engineering labs — studying the effects of pH on cement, soil, and other materials — by holding pH steady automatically instead of requiring someone to titrate by hand throughout a run.

Hardware

  • Raspberry Pi 4 — onboard compute running the controller and web backend
  • Atlas Scientific EZO-pH circuit — pH measurement
  • Two Atlas Scientific EZO-PMP peristaltic pumps — acid and base dosing
  • i3 Interlink — electrical isolation between the Pi and pump/sensor circuits
  • Hosyond capacitive touchscreen — local live readout and control

Software

Built around a Flask web backend with a modular structure:

  • Core controller runs a background dosing loop that doses within a configurable deadband around the setpoint
  • Hardware drivers handle low-level I2C communication with the EZO devices
  • REST API for remote control and integration with other tools/scripts
  • Web dashboard for live pH charting, manual pump priming/control, and calibration wizards
  • Session logging to CSV for after-the-fact analysis
  • Tailscale VPN + HTTP Basic Auth for secure remote access to the dashboard

Web Dashboard

Live pH readout against a target setpoint, manual pump control, and a real-time chart of pH and dosing volume over time.

I2C addressing, dosing parameters (deadband, dose per cycle, poll interval), and a guided pH probe calibration wizard (mid/low/high point) are all configurable from the dashboard.