OpenReef

OpenReef explores a difficult task: automating colorimetric nutrient tests with parts a maker can inspect. A Raspberry Pi web application controls a light sensor, pumps, stirring motors and solenoid valves, then applies editable calibration data to phosphate or nitrate assays. The documentation states wavelengths, approximate ranges, reaction timing, system architecture and an estimated build cost. Hardware designs and Python code are open, while command sequences can be saved to repeat fluid handling. It is a promising platform for experimentation, teaching and custom reef monitoring.

This remains an evolving DIY instrument, not a certified laboratory analyzer. The project lists assay-specific calibration, enclosure work and a PCB among unfinished items, and reagents involving cadmium reduction demand careful handling and disposal. Bubbles, dirty cuvettes, reagent age, timing and calibration drift can all produce plausible but wrong numbers. A result that would trigger a large intervention should be confirmed by another method. Builders need leak containment and manual oversight before connecting automated fluid paths anywhere near an established aquarium.