With the rise of single board computers such as the Raspberry Pi and Arduino Uno a market has emerged for a wide range of sensors that can easily be incorporated into these systems. For this application, the Adafruit AS7341 sensor looked ideal. The sensor measures light across 10 wavelength 'channels' (IR, 8 visible spectrum wavelengths, and a 'clear' channel that covers that entire spectrum) and can be interfaced with easily using I 2 C (Inter-Integrated Circuit). If a white LED was used to irradiate the reactor pipe, then the absorbance of the fluid within the pipe could be determined at multiple wavelengths simultaneously -providing richer data than the previously published inline detectors at a similar low cost.