A process and apparatus for increasing biological activity in waste treatment ponds and lagoons. In this process a floating fluid circulator having an annular space between nested frusto-conical surfaces is operated in a pond or lagoon. An aerator within the scope of the floating fluid circulator is provided. That aerator includes an upper float chassis having a frusto-conical configuration, a sectional diverter arranged in a lower portion of the upper float chassis, the sectional aerator having a lower diverter portion and motor driven means mounted on the upper float chassis connected to a rotatable impeller.