Various models available (see data sheet below for options). This model, the online TOL 3 White Light (higher
sensitivity for small particles, required by US EPA for online) analyzes from 1-100 NTU. See how fast and easy it is to calibrate in this Youtube video
. The low maintenance turbidimeter has a bubble rejection system, and some models come with optional ultrasonic autoclean feature which works to give accurate results and discourage water bubbles which can sway the turbidity number. A software system allows logging and data storage for multiple turbidimeters.