The 6538A water turbidity instrument from Unidata will measure and record water turbidity over the wide range of 0 NTU to 2,000 NTU in three automatically selected ranges. A high resolution of 0.2 NTU with sunlight filtering is achieved by using advanced digital processing. The interal data logger can store up to 60,000 readings, allowing long-term deployment at remote locations. RS-232, SDI-12 and 4-20mA interfaces are available for data retrieval or interfacing to other systems. Unidata, Card No. 193
