Abstract: A balance device for use in conjunction with a continuous fluid filter exchange system includes a balance beam stand, and a pair of beams pivotally mounted on the stand at respective levels above and below the filter. A source of substitution fluid for the exchange system is suspended from the upper beam while a reservoir for filtrate from the system is suspended from the lower beam. A supply tube devoid of pumps is provided for introducing substitution fluid from the source into the system, and a filtrate tube devoid of pumps is provided for conducting filtrate from the system to the reservoir. Automatic control means is provided on the stand for controlling the flow of fluid into the system as a function of the amount of filtrate collected in the reservoir, and the control means is mechanically coupled to the beams. The device further includes automatic shut-off for terminating the flow of filtrate to the reservoir when the source of substitution fluid becomes empty.