30 day periods were chosen due to the limitations of the dissolved oxygen membrane and battery power. At the end of each 30 day period, the YSI is brought back into the lab for downloading, cleaning, and recalibration. Data is downloaded on PC and graphs are printed using the PC 6000 software. Sonde body and probes are cleaned. DO membrane is changed and allowed to re-equilibrate for at least one hour before calibration.
Calibration is as outlined in the user manual.
Buffer solutions of pH 7 and pH 10 are purchased from a scientific supply house and used for two point calibration. A salinity standard of 32.035 ppt is also purchased and used for calibration. After approximately four hours of down time, the YSIs are redeployed for another 30 days. Elkhorn Slough is located on the West Coast of the United States in Central California. It connects with the Pacific Ocean in central Monterey Bay near Moss Landing, California.