When being exposed to the red light (wavelength, 620–630 nm), blue light
(wavelength, 465–475 nm) and green light (wavelength, 522–532 nm), the maximum dry
matter contents of Spirulina were 1.346 g/L, 1.179 g/L and 1.081 g/L, respectively, indicating
that the red light was the best light source for the growth of Spirulina as a highest growth
rate with an dramatic increase of 56.69% (compared to the control group) in the dry matter
content was observed. 8 h were proved to be the best exposure time of red light for the
growth of Spirulina within one day, where a dry matter content of 1.440 g/L was found. This
was 67.64% higher than that of the control group.