cell. This will affect the accuracy of cell density estimates
derived with these instruments.
An inexpensive way to estimate algal density in large
cultures is to use a “Secchi disk,” a technique that has
been used by field biologists for decades. Once calibrated
to the microalga species in culture, Secchi disks can
provide a reasonably accurate estimate of algal cell density
(Hoff and Snell, 2008).