An apparatus for detecting developer liquid (108) level in a plate developer section tank (104) includes a reflective surface (204) installed on at least on one edge of the developer tank; a light emitter (232) which emits light onto the reflective surface; a light detector (236) adapted to detect reflected light from the reflective surface, wherein the light emitter and the light detector are positioned relative to the reflective surface such that the emitted light from the light emitter is deflected by the developer liquid hitting the reflective surface at 90 degrees.