Water quality

The water quality monitor collects and reports measurements from sensors suspended in the ocean. Currently we are upgrading our prototype and plan to have it back at Surfside in a week or so.

Expanding on our previous water quality experiments, this effort seeks to develop a system for continuous monitoring of aquatic environmental parameters that can be installed off grid, powered by solar panels and communicating through GSM networks. Once operational, this system will be tested against commercial water quality meters and standardized monitoring methods to validate its accuracy.

During a two-month coding extravaganza, Manuel and Sean built the SurfsideSensors repository and prototype environmental monitoring stations for water and air quality. The stations use the same code, with different libraries and deployments for different sensors.

The water quality station, named WAP (water assessing probes), makes use of affordable and high precision probes manufactured by Atlas Scientific. For this station, the included probes measure temperature, pH, electrical conductivity, and dissolved oxygen. Each probe uses a signal interpreting communication circuit that takes the raw signal from the probe, and sends it to the microcontroller on request. The microcontroller that was used includes an onboard battery holder, solar panel port, gps receiver, SD card slot, and a GSM modem with SIM card. This avoids having to find and buy all of these components separately and reduces risk of wiring something up wrong. The enclosure was inspired by the design of MakerBuoy, which uses a watertight utility box and a bottom tube to keep it upright and protect the probes.

The initial development focused on software, followed by construction of a custom circuit board to mount the components. The enclosure was produced last, and the prototype was calibrated and installed on August 22 at Surfside Marina. The unit worked as expected except for the readings of the pH sensor, which fluctuated a lot and reported readings that didn’t make sense for ocean water. After two weeks the unit was removed from the water and inspected. Attempts to recalibrate didn’t work as expected, so we thought that the sensor might have been damaged or defective. Biofouling was observed on the device, which was a concern from the start. Awaiting a replacement pH sensor and restocking of calibration fluids, WAPv1 is currently back at the lab for servicing.