A fluid-based spring counterbalance mechanism comprising an elastic flexible fluid-based spring disposed between a first plate and a second plate, each plate having a surface in contact with an end of the fluid-based spring. The counterbalance mechanism supports some or all of the weight of a movable barrier. A mechanism is configured to compress the flexible fluid-based spring between the respective surfaces of the two plates in response to motion of the movable barrier. By compressing the fluid-based spring, the counterbalance mechanism provides a force opposed to movement of the movable barrier.