When measuring chlorophyll levels using the C-FLUOR or Cyclops-7, a blue excitation configuration is recommended for use in aquatic habitats that have low levels of dissolved organics. Dissolved organic matter (DOM) significantly interferes with blue excitation so red excitation is recommended in high DOM environments. Also, blue excitation is more sensitive to non-cyanobacteria groups, known as eukaryotic algae. If you are looking to research these organism groups in a low DOM environment, a blue excitation configuration may be the best option for you.