In the process of controlling the pH level of water manually there is a risk of controlling pH levels directly in contact with hazardous chemicals such as HCl and NaOH. The two chemicals are chemicals that can be used to regulate the pH level of water, but both of these chemicals are included in corrosive materials which can cause damage to the skin or eyes if there is direct contact with the two materials. This study aims to design a system to control the pH of water in the form of a tool that can monitor and control the pH level of water automatically in order to reduce the risk of exposure to hazardous chemicals and facilitate the work of officers. This system uses a NodeMCU ESP8266 microcontroller controller which has an input in the form of a pH sensor and a water level sensor. The system output is in the form of 3 water pumps and 2 diaphragm pumps. NodeMCU will adjust the diaphragm pump speed by using the Sugeno Fuzzy logic method. By utilizing the Internet of Things (IoT) technology, the condition of the pH value of water and pumps can be monitored online via a smartphone making it easier to monitor at any time. The application used is the Blynk application based on the Android Operating System. The quality of the internet network connection connected to NodeMCU is very influential on sending data to CloudBlynk. Testing the diaphragm pump speed value is regulated by Sugeno fuzzy logic based on the readable pH value. Based on testing the pH of water, this system successfully controlled the pH of water with a capacity of 8 liters with a submersible pump speed of 1.31l / min, the highest pH value of the experiment 11.14 with a duration of 213 seconds, and the lowest pH value of 2.01 with a duration of 260 seconds

Keywords : pH, Internet of Things (IoT), Fuzzy Logic, NodeMcu ESP8266, Smartphone.