When measuring chlorophyll levels using the C-FLUOR, a red excitation configuration is recommended for use in aquatic habitats that have high dissolved organics. Unlike blue excitation, red excitation does not have as much interference from dissolved organic matter (DOM) because DOM particles absorb blue excitation energy, not red. Also, a red excitation configuration is more sensitive to prokaryotic algae, also known as blue/green algae or cyanobacteria. If you are looking to research this type of organism in a high DOM habitat, a red excitation configuration may be right for you.