WTW Measurement Systems, of Ft. Myers, Fla., has announced the availability of VisoTurb and ViSolid sensors with a breakthrough, new, ultrasonic cleaning system that prevents accumulation of any kind of contaminants on the optical windows. Virtually maintenance free, the VisoTurb Turbidity Sensor and the ViSolid Suspended Solids Sensor, provide long term reliability and accuracy for all measurements. In addition, enormously wide measuring ranges are featured.