There are many kinds of chlorophyll and the most common types are the bluish-green chlorophyll-a (Chl-a) and the yellowish-green chlorophyll-b (Chl-b). The compositions of Chl-a and Chl-b are very similar. Both of them are able to absorb sunlight, yet, they only differ in their internal structure and the wavelength of light they absorb. The ratio of Chl-a to Chl-b in land plants is approximately 3 to1. When the concentration of Chl-a is high in water, it represents the over production of algae and indicates indirectly the degree of eutrophication.