Water velocities in the centimeter or millimeter per second range are measurable by only a few instruments. Experimental laboratory studies frequently require such measurements. An inexpensive optical hydrogen bubble tracing device is described for velocity measurements in the range 0.5 to 8 cm/s. Modification to a thymol blue (pH) tracer method extends its applicability to the range 0.1 to 1.0 cm/s. Design and operational characteristics of the hydrogen bubble/thymol blue current meter are described. Analysis of low Reynolds number flow around a cylinder is used to explain meter calibration characteristics.