First, I look at the petri dish with just water (so I can use the graph as a control). Then I look at the petri dish with some algae in it. I expect the intensity of the algae to be at certain wavelength (like 400-450 and 650-700 as those are the wavelengths for chorophyll). Therefore, the graph with the algae should have those wavelengths reduced as compared to the graph with just water since at those wavelength, light should be absorbed, correct? More growth of algae should correspond to an increase in chorophyll present, with more absorption at those wavelength and there should be lower intensity at the wavelengths associated with chorophyll, right? However, what I am seeing are higher intensities in the spectra for the algae vs that of water. What am I missing? Any advice or help would be appreciated.