Water and wastewater plant operators use this handheld sludge level detector to monitor liquid-solids interface levels in clarifiers, tanks, ponds and lagoons, helping to eliminate unnecessary pumping/dredging, monitor for regulatory compliance and prevent carryover. Compact and weatherproof, it is ideal for use on catwalks and boats. Users quickly determine sludge depth readings from numbered markers on the cable. A thumb-adjustable control allows the user to fine-tune the instrument’s optical sensitivity, and detect silt, sludge and biosolids in densities ranging from clear surfaces or light flocs to the thick blankets of murky lagoons.