The SEBA-pneumatic gauge type PS- light-2 serves as a robust, economic and reliable measuring system for monitoring water level in surface waters. The measuring principle is the proportioning or bubbler system, based upon the other well-known SEBA instruments in the PS-series. An integrated, highly efficient mini compressor, bubbles air through the pressure tube into the water at adjustable intervals. In addition, The resultant pressure in the tube corresponds exactly to the hydro static pressure above the mouthpiece.