Abstract: A compact hydraulic particle separator apparatus is disclosed. The disclosed apparatus comprises an upper chamber and a lower chamber separated by a partition. A liquid fluid flow upwelling through the partition from the lower chamber is caused to mix with tangential jet of fluid flowing introduced above the partition in the upper chamber produces an upwardly-flowing cyclonic flow within the upper chamber. Particle mixtures containing low- and high-density particles and other solids are introduced into the upper chamber through a feed tube having a mouth that is offset from the center of the upper chamber. Low-density particles are immediately entrained in the cyclonic flow and swept upward and exit the apparatus.