A method for operating a circulating sub in a well includes opening a port of the circulating sub, including: dropping a ball into a drill pipe containing a downhole fluid; and seating the ball on an actuator slidably disposed concentrically within the drill pipe, in which seating the ball on the actuator causes motion of the actuator relative to the drill pipe to open a port defined in a wall of the drill pipe. The method includes closing the port of the circulating sub, including: introducing a solvent different from the downhole fluid into the drill pipe, in which a solubility of the ball in the solvent is greater than a solubility of the ball in the downhole fluid; and degrading the ball in the solvent, in which the degrading of the ball causes motion of the actuator relative to the drill pipe to close the port.