This invention is directed to a stirring apparatus comprising: a plurality of blades having between a 5° to 180° twist along the length of their axis attached perpendicularly to a shaft so that a downward fluid flow is created when the shaft is rotated by a rotary drive; and, a plurality of standards attached to the plurality of blades separating the plurality of blades and arranged parallel to the shaft and rotated between 0° and 25° relative to a plane defined by the blades and the standards so that an inward fluid flow is created when the shaft is rotated and a bottom blade connected to the standards.