Pipetting robot for determining at least one predetermined property of sample water, in particular aquarium water, comprising - a measuring cuvette for holding the sample water, - at least one reagent container for holding a liquid reagent, by means of which reagent a color change representative of the predetermined property can be brought about in the sample water, - a pump for transferring the reagent from the reagent container into the measuring cuvette via a reagent inlet at an upper side of the measuring cuvette, whereby the reagent can be dripped into the measuring cuvette, and - a camera for recording images of the measuring cuvette and the sample water in the measuring cuvette, - a background which is arranged on the side of the measuring cuvette facing away from the camera and lies in the field of view of the camera, wherein areas in at least two different colors are depicted on the background in a predetermined pattern for providing contrast, wherein the pattern is preferably a checkerboard pattern with black and white areas, and wherein at least three reference color points are depicted on the background for providing color reference, of which at least one is red, one is green and one is blue, and - an evaluation unit which is designed to determine the filling quantity of the sample water in the measuring cuvette on the basis of the images recorded by the camera, to count the number of reagent droplets dripping into the measuring cuvette and to determine the at least one predetermined property of the sample water from the counted number of reagent droplets in combination with the color change of the sample water determined from the images. - a measuring cuvette for holding the sample water, - at least one reagent container for holding a liquid reagent, by means of which reagent a color change representative of the predetermined property can be brought about in the sample water, - a pump for transferring the reagent from the reagent container into the measuring cuvette via a reagent inlet at an upper side of the measuring cuvette, whereby the reagent can be dripped into the measuring cuvette, and - a camera for recording images of the measuring cuvette and the sample water in the measuring cuvette, - a background which is arranged on the side of the measuring cuvette facing away from the camera and lies in the field of view of the camera, wherein areas in at least two different colors are depicted on the background in a predetermined pattern for providing contrast, wherein the pattern is preferably a checkerboard pattern with black and white areas, and wherein at least three reference color points are depicted on the background for providing color reference, of which at least one is red, one is green and one is blue, and - an evaluation unit which is designed to determine the filling quantity of the sample water in the measuring cuvette on the basis of the images recorded by the camera, to count the number of reagent droplets dripping into the measuring cuvette and to determine the at least one predetermined property of the sample water from the counted number of reagent droplets in combination with the color change of the sample water determined from the images.