Blue-green algae (BGA), also known as cyanobacteria, are photosynthetic bacteria that can grow in fresh and marine water and can be blue, green, red and black in color. BGA reduce nitrogen and carbon in water, but also deplete dissolved oxygen in excess. Monitoring BGAs is important because they pose a serious threat to water quality, ecosystem stability, surface drinking water supplies and public health through the production of toxins and the large biomass generated by algal blooms.

Apure measures blue-green algae in real time through in vivo fluorescence technology. These sensors are fixed response fluorometers, which means they excite algae in the water at a fixed wavelength (520nm or 590nm). They then measure the subsequent fluorescence emitted (>575nm and >655nm). The method directly detects the fluorescence of specific pigments in live algal cells and determines the relative algal biomass. the BGA-206A sensor is not interfered with by chlorophyll or turbidity.