Xylem 6-Series Multiparameter - Manual (Page 316)

Turbidity Measurements Appendix E
YSI Incorporated Environmental Monitoring Systems Operations Manual E- 3
For most applications involving both spot sampling and monitoring, the following settings are
recommended with regard to data processing:
ο
In 3-Sensor, activate the “Turb Spike Filter”
ο
In 4-Data Filter, “Enable” the filter.
ο
In 4-Data Filter, “Disable” the “Wait for Filter” selection.
ο
In 4-Data Filter for turbidity, set the Time Constant to 12
ο
In 4-Data Filter for turbidity, set the Threshold to 0.010
These settings will normally produce data that is reflective of the “average” turbidity without having any
significant effect on the response times of the other sensors. Increasing the values of the time constant,
threshold, or both can further smooth the turbidity values, but also are likely to increase the apparent
response time of the sensor.
How do I set up 6-series sondes for logging turbidity data to internal memory?
First, as outlined above, set the data filter and turbidity spike filter settings as recommended in the previous
question/answer. Second, access 2-Setup in the Advanced submenu and make certain that the “Turb
Wipes” entry is set to “1”. Finally, in the same submenu, set the “Twipe Int” parameter (in minutes) to the
same value as the sample interval for which data will be transmitted to the logging device. For example, if
Sample Interval is set to” 900 seconds” (15 minutes) in the Discrete Sample Run menu or “15 minutes” in
the Unattended mode, set “Twipe Int” to “15”. Under these conditions, the turbidity wiper will be
activated in a single bi-directional cleaning motion every 15 minutes to clean bubbles and fouling from the
optics of the probe and minimize the chance of corrupted readings due to these factors. Note, however,
that for Unattended applications with the sonde where data is being logged to internal sonde memory and
“Autosleep RS232” is activated, it is only necessary that the value of Twipe Int be less than that of the
sample interval selected for the Unattended study. Thus, if Twipe Int is set to 5 minutes and the
Unattended sample interval is set to 15 minutes, the sensor will only be cleaned every 15 minutes. For this
reason, if you use your sonde primarily for Unattended monitoring, it is recommended that you leave
Twipe Int at the default setting of “5”, even though this is different from your sample interval. As outlined
in the manual, in sites where fouling is more prevalent, it may be necessary to set “Turb Wipes” to a higher
value, but a setting of “1” will be adequate for most water.
After sonde software setup is complete as outlined above, attach the sonde to a computer or a 650 MDS and
calibrate all sensors (including turbidity). Then set up an Unattended study at your desired sample interval
and deploy the sonde without cable connections for later data upload and analysis.
How do I set up 6-series sondes with turbidity for use with a Data Collection Platform (DCP?
If your 6-series sonde with a turbidity sensor will be attached to a data collection platform, you should
calibrate the sensors (including turbidity) prior to DCP connection. You should also make sure that the
“SDI12/M” factor which is found in the Advanced|Sensor menu is set to a value of “1” to ensure proper
wiping of the turbidity probe during deployment on the DCP. Then connect the sonde to the data
collection platform using the proper cable/adapter and begin sampling according to the instruction manual.