SEECHI PLATE

A 205 mm square metal plate with 200 mm round alternating black and white quadrants for estimating the turbidity of water in ponds, rivers etc. The plate is lowered into the water until the black and white quadrants can no longer be differentiated. Depth is noted and then the plate is raised until the quadrants can just be differentiated. Depth is again noted. The mean of two depths is taken as an index of relative turbidity. Cord supplied with the plate can either be knotted at 0.5 m interval or some colored markers can be tied for noting the depth.