This study presents a simple experimental method for studying the influence of the proton concentration starting from the first second of CAC hydration. Therefore, we investigate different inorganic acids as retarders for calcium aluminate cements in a highly diluted suspension (high w/s-ratio). This approach was rarely conducted before for CAC . Our experimental setup facilitates the usage of a conductivity sensor and ion-selective electrodes, allowing real-time acquisition of data on the pore solution composition from the beginning of hydration. We focus on the effect of the corresponding anion of the acids and the influence of the CA content and the CAC surface area. Additionally, isothermal calorimetry measurements were performed on CAC pastes under the influence of different inorganic acids to characterize their impact on the main CA reaction at normal water-to-solid ratios.