A reduced air hydrocyclone unit includes a hydrocyclone having a cylindrical section, a conical base having an underflow outlet formed in its apex, and an overflow outlet on an upper end of the cylindrical section. An underflow basin collects underflow material. Overflow material flows through an overflow line. An exhaust fan of the reduced air hydrocyclone unit withdraws from the overflow material in the overflow line a portion of an amount of air introduced through the apex of the hydrocyclone. A reduced air fluid system includes the reduced air hydrocyclone unit, a fluid tank in fluid communication with the overflow line of the reduced air hydrocyclone unit, and a reduced air hopper for mixing a solid material with a fluid contained in the fluid tank to form a slurry. A liquid barrier inlet of the reduced air hopper creates a liquid barrier to prevent air introduction into the slurry.