Clarifiers are settling tanks used to remove solid particulates from wastewater. Such impurities fall into two categories, sludge which falls to the bottom of the tank, and scum which floats and collects on the surface of the liquid. The total clarification process requires multiple stages or tanks, with each stage achieving a greater degree of purification. The movement of wastewater from one clarifier to the next is gravity fed, and fine tuning the speed of movement is critical to the process. At this Midwest municipal treatment facility, an EchoSonic ultrasonic level transmitter is installed in each clarifier. The non-contact sensor provides continuous level data to the SCADA, which in turn, correlates level height with flow rate, to determine and control the speed of gravity flow through clarification. EchoSonic is reliable clarifier level measurement.