Markland’s Detector monitors solid-liquid interface levels in clarifiers, sedimentation basins and tanks, and automates silt/sludge/biosolids removal. It allows operators to program de-sludge pumps to operate only when necessary, preventing carryover, optimizing feed density for enhanced dewatering, reducing energy usage. The slim profile and use of high-intensity infrared light make this process control instrument ideal for obstructed/constricted areas. In addition, in DAF units, the detector can adjust surface skimmer speeds to match variations in the thickness of the floating sludge layer; in SBRs, it can control the decant valve to minimize cycle times. No calibration required.