Method for producing dialysis fluid for use in extracorporeal blood treatment on an apparatus for extracorporeal blood treatment, comprising the steps of delivering water, preferably osmotic or high-purity water, via a main line (S2); delivering a basic fluid and introducing the basic fluid at a feeding point into the main line ; delivering an acidic fluid and introducing the acidic fluid at a feeding point into the main line ; measuring at least one physical and/or chemical parameter of the water-fluid mixture consisting of water, the acidic fluid and/or the basic fluid by means of a first measuring device (S.3.2); and adjusting the delivery rates for the water, the acid fluid and/or the basic fluid by a control and regulating unit as a function of the measured value detected, wherein the measuring of the at least one physical and/or chemical parameter is carried out by means of a measuring device arranged at a section of the main line located downstream of the feeding point for the acidic fluid and the feeding point for the basic fluid, respectively, characterized in that the control and regulating unit controls at least temporarily the feeding of the acid fluid and the basic fluid in such a way that, over a predetermined period of time or a predetermined interval, only a first fluid from among the acid and basic fluids is fed into the main line , and at first the parameter of the water-fluid mixture containing only the first fluid is measured and, based thereon, the dosage or delivery rate of the first fluid is determined; thereupon the feeding of the first fluid is interrupted and instead a second fluid from among the acidic and basic fluids is fed, wherein the parameter of the water-fluid mixture with only the second fluid is measured and based thereon the dosage or delivery rate of the second fluid is determined and finally both fluids are fed with the afore-determined dosages or delivery rates. delivering water, preferably osmotic or high-purity water, via a main line (S2); delivering a basic fluid and introducing the basic fluid at a feeding point into the main line ; delivering an acidic fluid and introducing the acidic fluid at a feeding point into the main line ; measuring at least one physical and/or chemical parameter of the water-fluid mixture consisting of water, the acidic fluid and/or the basic fluid by means of a first measuring device (S.3.2); and adjusting the delivery rates for the water, the acid fluid and/or the basic fluid by a control and regulating unit as a function of the measured value detected, wherein the measuring of the at least one physical and/or chemical parameter is carried out by means of a measuring device arranged at a section of the main line located downstream of the feeding point for the acidic fluid and the feeding point for the basic fluid, respectively, characterized in that the control and regulating unit controls at least temporarily the feeding of the acid fluid and the basic fluid in such a way that, over a predetermined period of time or a predetermined interval, only a first fluid from among the acid and basic fluids is fed into the main line , and at first the parameter of the water-fluid mixture containing only the first fluid is measured and, based thereon, the dosage or delivery rate of the first fluid is determined; thereupon the feeding of the first fluid is interrupted and instead a second fluid from among the acidic and basic fluids is fed, wherein the parameter of the water-fluid mixture with only the second fluid is measured and based thereon the dosage or delivery rate of the second fluid is determined and finally both fluids are fed with the afore-determined dosages or delivery rates. <EOS>