An echo sounding system includes a acoustic gun which is mounted to the wellhead of a borehole. The acoustic gun produces a acoustic pulse which is transmitted down the borehole. A tubing string is installed in the borehole and it has substantially evenly spaced collars. Fluid is pumped from the borehole, or well, by use of a reciprocating pump driven by a pump rod extending to the surface. Fluid is received from a surrounding formation and collects in the borehole. The acoustic pulse produces reflections when it strikes the tubing collars and the surface of the fluid. A microphone detects the reflections to produce a return signal. This signal is digitized and stored. The digitized signal is processed to detect the rate of the collar reflections and the stored signal is narrowband filtered with a passband filter centered at the rate of receipt of the collars. The data signal is further processed to determine the time of occurrence of the acoustic pulse and the liquid surface reflection. Each cycle of the narrowband filtered signal corresponds to one collar reflection. In this signal, each cycle is counted, and extrapolation used when necessary to produce a collar count extending from the surface to the liquid surface. This is multiplied by the average joint length to produce the depth to the liquid surface. The data signal and various well parameters and a schematic of the well are displayed for use by an operator. The system further detects the liquid level and displays it as a marker on the data signal. An operator can use the automatically determined marker or move it to another position. Finally, the operator is provided with optimum operating parameters for achieving maximum production from the well.