A system for enhancing the separation of particles or fluids from water is disclosed. A tank or bioreactor is provided with an open submersible acoustophoretic separator. The separator captures and holds fluid droplets or particles such as cells, permitting them to coalesce or agglomerate until they are large enough and have sufficient buoyant or weight force to float/sink to the top/bottom of the tank or bioreactor. In a tank or bioreactor, the separator captures and holds particles until they are large enough that their weight causes them to settle out of the host fluid. The acoustophoretic device thus speeds up separation of the particles or droplets from the host fluid.