The Sludge Gun from Markland Specialty Engineering measures silt/biosolids interface levels in clarifiers, tanks and lagoons, and helps provide valuable level profiles. This hand-held detector allows users to monitor biosolids bed depth for regulatory compliance and prevention of carryover, and to eliminate unnecessary pumping/dredging. It uses high-intensity infrared light to detect densities ranging from light flocs to thick blankets. As the sensor is lowered into the tank/pond, the instrument emits an audible tone, which varies in volume and pitch depending upon the concentration of suspended solids. The blanket and overlying cloudy layer are located by observing depth markers on the cable. The high-power Model 10-HP excels at finding the level in murky lagoons, while the Model 10-LP detects clear liquid surfaces. It is compact, weatherproof and convenient for boats or catwalks, with no calibration necessary. 855/873-7791; www.sludgecontrols.com