http://web.pdx.edu/~rueterj/algae/course_notes/growth_rate.htm

Growth Rate of Algae in Nutrient Replete Media

If algae are allowed to grow with plenty of light and nutrients they will demonstrate exponential growth. The maximum rate at which they grow is called mu_max or max. The specific growth rate of a culture is in terms of new cells per cell per time. Mu has the dimensions of time^-1.

The specific growth rate is not the doubling time or the rate at which a culture will double, although it is related to these concepts.