Abstract: An asymmetric hydrocyclone is modified and controlled so as to effectively remove contaminants of substantially neutral buoyancy from a paper cellulosic pulp. More specifically, a method includes prepositioning a substantially frusto-conically-shaped separation chamber of the hydrocyclone at an oblique angle to a vertical axis, and introducing a cellulosic pulp through an inlet and into the separation chamber for separation processing. As is known, the pulp composition forms a downwardly-directed helical path, which in turn establishes an opposingly directed, upward helical air core. Centrifugal forces motivate heavier particles toward the sidewalls of the separation chamber and lighter particles are urged toward the air core, with particles of substantially neutral buoyancy circumferentially collected in an intermediate region, but in relatively close proximity to the air core.