Dosing apparatus for dosing a composition, comprising: a) at least one box for keeping the composition or a capsule containing the composition, b) a solution reservoir for preparing a composition solution with a pre-defined concentration of the composition in solution, wherein the composition solution with said pre-defined concentration of the composition in solution can be further used as a use solution, c) at least one spray means coupled to the box for bringing the composition being in the box into contact with a solvent liquid, such that an amount of the composition dissolves and the thus resulting composition solution flows into the solution reservoir, d) at least one spray line, for feeding the spray means with the solvent liquid, e) a supply line comprising a liquid connection and a solenoid valve for supplying fresh liquid, preferably water, to the solution reservoir, f) measuring means for measuring the conductivity of the composition solution, g) at least one motorized feed pump for moving the composition solution, the solving liquid, the use solution, and/or the fresh liquid, and h) an electronic control unit for controlling the operation of the dosing apparatus, characterized in that, the dosing apparatus additionally comprises: i) a day tank for storing the use solution, such that the composition solution with the pre-defined concentration of the composition in solution can be prepared without changing the concentration of the composition in solution in the use solution stored within the day tank, j) a flushing out line, connecting the solution reservoir with the day tank for discharging the composition solution with the pre-defined concentration of the composition in solution from the solution reservoir into the day tank, thereby refilling the day tank with the use solution, k) a discharge line, which is connected to the day tank, comprising a discharge for discharging the use solution from the day tank. a) at least one box for keeping the composition or a capsule containing the composition, b) a solution reservoir for preparing a composition solution with a pre-defined concentration of the composition in solution, wherein the composition solution with said pre-defined concentration of the composition in solution can be further used as a use solution, c) at least one spray means coupled to the box for bringing the composition being in the box into contact with a solvent liquid, such that an amount of the composition dissolves and the thus resulting composition solution flows into the solution reservoir, d) at least one spray line, for feeding the spray means with the solvent liquid, e) a supply line comprising a liquid connection and a solenoid valve for supplying fresh liquid, preferably water, to the solution reservoir, f) measuring means for measuring the conductivity of the composition solution, g) at least one motorized feed pump for moving the composition solution, the solving liquid, the use solution, and/or the fresh liquid, and h) an electronic control unit for controlling the operation of the dosing apparatus, i) a day tank for storing the use solution, such that the composition solution with the pre-defined concentration of the composition in solution can be prepared without changing the concentration of the composition in solution in the use solution stored within the day tank, j) a flushing out line, connecting the solution reservoir with the day tank for discharging the composition solution with the pre-defined concentration of the composition in solution from the solution reservoir into the day tank, thereby refilling the day tank with the use solution, k) a discharge line, which is connected to the day tank, comprising a discharge for discharging the use solution from the day tank.