A system for aerating spent water from an aquaculture vessel (1) incorporating an oxygen sensor (1a) for providing a signal transmission, via a control panel, for opening or closing a control valve (V6) and creating a bypass recycle loop via an aeration/degassing module (10) through a pipe (6A) to a circulation pump (7)5creating a water level change in the degassing module (10), wherein changes produce gravitational pressure levels, giving a water flow (13) allowing water re-oxidizing saturation back to the vessel (1) and transferring said water into an aeration/degassing transition zone (10.1) via an atmospheric UVGI intake (11), wherein said pump (7) distributes the filtered water from primary and secondary 10filtration modules (3,5) into a piping spool (8) through a separator (14) or directly to a Borda-Carnot design, self-balancing, low energy aeration unit (9-1).(Fig. 1)15
