Arduino based Diver Propelled Turbidity Measuring probe.
In the early 2017 dive season during some of my first dives in the New York Harbor proper, a fascinating and quite inspiring trend began to emerge. I noticed without fail that the turbidity(visibility) of the water near the oyster cages placed by the billion oyster project was markedly improved as compared to the surrounding water. During each dive I would gawk at the visibility around the cages at an almost loss of words. If there was any doubt in my head about whether the oysters were doing anything or not, it was instantly destroyed. I knew that me gasping over the com lines that the visibility was “f*cking insane”, “totally ridiculous!” or me begging that somebody else be here to witness this with me weren’t the most scientific methods to describe the effect that the oysters were having on the quality of the water. As a scientist, I know that there isn’t much that can beat cold hard numbers, so I set out to create a device that could empirically test my accurate, but sometimes vulgar, anecdotes.
The device and its sensors:
The basic requirements of this device are that it is relatively easy to handle underwater, the ability to be upgraded with new sensors relatively easily and that it be cost effective to produce. The electronics of the device are housed within a 4 inch diameter pvc pipe. An end cap is glued permanently in place on one end and a removable end cap is placed on the other. Holes are drilled into the removable end cap to allow for sensors to be potted in with an epoxy adhesive. The electronics are velcroed onto a simple tray system which allows for easy removal for servicing and testing. On top of the device a small section about 3cm by 3cm of the pvc pipe is removed and replaced by a clear square of acrylic to allow for the viewing of the LCD screen. There are two controls which are sealed using Underwater camera housing control glands, One button, when pressed, will take a measurement at the moment, and the other button will toggle between continuous measurement, every 500ms, and single measurement, every time the button is pressed.
The device records the data to a Micro sd card which makes it easy to export into a program such as Microsoft Excel to create a Graph of the data. Currently there are two fully functioning sensors, temperature and turbidity. On my shortlist of tasks is to speak with various scientists working for the Billion Oyster Project and decide on 1 more sensor that would be appropriate to add. In addition to the turbidity and temperature sensors, I am also currently working on a Chlorophyll Fluorometer which works by measuring the fluorescence of Chlorophyll found in photosynthetic organisms to ascertain the population of algae in a specific sample of water. This sensor will also be mounted to the turbidity measuring device.
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