A Little Biofouling Can Go a Long Way—to Screwing Up Your Data

Biofouling. The bane of existence for many monitoring programs. Even a little spot of the stuff on water quality sensor optics can affect your data.

Case in point: Individual wipers on each of these sensors (photo below) are doing a pretty good job at cleaning the sensor optics. But notice the small ring of soft organisms around the far outside edges of the sensors, which formed after 8 weeks.

Tip: Thicker foam pads on the sensors’ wipers can take care of that fouling, before the barnacles build up to behemoth proportions.

Case in point 2: Notice the stringy biofouling on the top of the wiper (photo below). In many cases, this fouling shouldn’t cause a problem with data collection, because it is situated away from the optics. But notice what happens when the sensor is submerged in warm, estuarine water for 8 weeks. The algal strands fan out and wave around in front of the optics. This motion subsequently causes spikes and an offset in the data.









Tip: Small pieces of copper tape applied over the screw at the top of the wiper shaft will eliminate this potential problem area.

What’s next? New YSI instruments take these lessons from biofouling and offer a design that cuts down on biofouling even further. After 8 weeks, all sensors on a new EXO sonde–with a large, central wiper–are free of fouling. Data protected!


10 Tips to Prevent Biofouling


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