Backscattering
Commercial backscattering meters are open path measurements. Therefore, we require an enclosure of known (and minimal) effect on backscattered light in order to deploy a backscattering meter in-line. To determine accurate measurements of particulate backscattering, it is also critical to assess (and later remove) the impact of reflections from the internal walls of the flow-through chamber on the measured signals. This can be accomplished by computing the difference between a measurement of pure water at a given temperature and salinity (obtained by re-filtering MilliQ water until the backscattering signal stabilizes) and the modeled backscattering of pure water at the same temperature and salinity. A large curved PVC elbow (septic clean-out), painted flat black, also can be used to minimize internal wall reflectance for backscattering measurements and is relatively inexpensive to fabricate. Comparisons between this latter device and the “casket” shaped enclosure have yet to be done.