A method of mixing aqueous solutions, which has the following steps: A) providing aqueous solutions in at least two separate storage containers, B) introducing the aqueous solutions into a mixing container by at least one respective dosing device so that a mixture of the aqueous solutions is produced, wherein the dosing device has the following components: 1) a dosing chamber having a displacement element which is arranged moveably in such a way that it is reciprocable between two points of maximum deflection S max and S min, wherein the volume of the dosing chamber in the position S max is at a maximum and in the position S min is at a minimum and wherein the spacing of S max and S min corresponds to a maximum stroke length H max, 2) an actuator for driving the displacement element which has an actuator input for an electrical actuation signal and is so constructed that an electrical actuation signal at the actuator input is converted into a mechanical movement, wherein introduction is effected by the displacement element performing an oscillating movement between two positions S A and S E within the range of S max and S min so that the aqueous solution is sucked out of the storage container into the dosing chamber by a suction stroke h S and is then pushed into the mixing container by a pressure stroke h D, wherein the spacing H A-E of the two positions S A and S E is less than or equal to the maximum stroke length H max, C) determining the amounts of the aqueous solutions introduced into the mixing container by dosing monitoring means and/or detecting a physical and/or chemical measurement value of the mixture of the aqueous solutions by a sensor, characterised in that D) the measurement values determined in C) are communicated to at least one stroke length closed-loop control and the stroke length closed-loop control adapts the movement of the actuator and thus the spacing H A-E of at least one dosing device in dependence on said measurement values, the stroke frequency being kept substantially identical. A) providing aqueous solutions in at least two separate storage containers, B) introducing the aqueous solutions into a mixing container by at least one respective dosing device so that a mixture of the aqueous solutions is produced, wherein the dosing device has the following components: 1) a dosing chamber having a displacement element which is arranged moveably in such a way that it is reciprocable between two points of maximum deflection S max and S min, wherein the volume of the dosing chamber in the position S max is at a maximum and in the position S min is at a minimum and wherein the spacing of S max and S min corresponds to a maximum stroke length H max, 2) an actuator for driving the displacement element which has an actuator input for an electrical actuation signal and is so constructed that an electrical actuation signal at the actuator input is converted into a mechanical movement, wherein introduction is effected by the displacement element performing an oscillating movement between two positions S A and S E within the range of S max and S min so that the aqueous solution is sucked out of the storage container into the dosing chamber by a suction stroke h S and is then pushed into the mixing container by a pressure stroke h D, wherein the spacing H A-E of the two positions S A and S E is less than or equal to the maximum stroke length H max, 1) a dosing chamber having a displacement element which is arranged moveably in such a way that it is reciprocable between two points of maximum deflection S max and S min, wherein the volume of the dosing chamber in the position S max is at a maximum and in the position S min is at a minimum and wherein the spacing of S max and S min corresponds to a maximum stroke length H max, 2) an actuator for driving the displacement element which has an actuator input for an electrical actuation signal and is so constructed that an electrical actuation signal at the actuator input is converted into a mechanical movement, C) determining the amounts of the aqueous solutions introduced into the mixing container by dosing monitoring means and/or detecting a physical and/or chemical measurement value of the mixture of the aqueous solutions by a sensor,