YSI ADV6600 - Manual (Page 192)

Appendix E. Chlorophyll Measurements
ADV6600
Y S I Environmental
Page 182
If you consistently observe periods in your monitoring study where the data is clearly
unreliable due to a large number of very high spikes, then you may have to take additional
precautions to minimize the effect.
My unattended monitoring data shows a large number of chlorophyll spikes that clearly do not
reflect the average phytoplankton content of the water. What is causing this effect and is there
anything I can do to minimize it?
This effect, shown in the initial chlorophyll readings in the figure below, can be caused by
the presence of subsurface macroscopic filamentous algae.
The flexible algal strands can become attached to the wiper arm and sometimes are resident
on the probe optics even after a cleaning cycle. The key to decreasing the spiking effect is
to minimize the free algae, which is present in the probe compartment of the sonde. This
can sometimes be accomplished by encasing the sonde guard in standard fiberglass window
screen wire which is available at most hardware stores and then anchoring the screen with
rubber bands as shown in the picture below.