in vivo, silicate, phosphate, nutrients, UV, oil, optical, cyanobacteria, field fluorometers, laboratory fluorometer, submersible fluorometers, submersible active fluorometer, on-line fluorometers, online fluorometer, chlorophyll, blue green algae, rhodamine, fluorescein, ammonium, CDOM, turbidity, absorbance, optical brighteners, fluorometer, algae fluorometer, chlorophyll fluorometer, rhodamine wt, rhodamine fluorometer, tracer dyes, dye tracing, dye fluorometer, in situ fluorometer, in-situ fluorometer, fluorometer, chlorophyll, fluorometer algae, handheld fluorometer, OEM fluorometers, environmental fluorometers, industrial fluorometers, chlorophyll measurements