<![CDATA[Control systems are widely applied in various fields, including fish farming. Water quality can decrease rapidly due to the deposition of feed residues, faeces, and metabolic waste of fish. The deposition causes the phosphate concentration to elevate; as a result, the water becomes murky. In addition, significant changes in pH in a short time cause physiological disturbances for fish. Aquarium water quality plays a vital role in the maintenance of aquarium fish; therefore, a system that can control and monitor water quality in fish farming is needed. The purpose of the study was to design as well as build an aquarium pH and turbidity control system and to assess the performance of the design produced. The system was designed using Arduino Uno ATmega328P as a microcontroller. This microcontroller was connected to sensor pH E-201 BNC, sensor turbidity SEN0189, ultrasonic sensor as a water level sensor, a relay as a pump controller, solenoid valve and 16x2 LCD as a monitor. The pH and turbidity setting point was based on the optimum living condition of Koi fish, which was entered manually through coding. For this study, an aquarium prototype was built with 40 x 25 x 28 cm dimensions. The results showed that the pH sensor error values for acid, alkaline and neutral water conditions were 0,35%, 0,72%, dan 0,49%, respectively, while the accuracies were 99.65 %, 99.28%, and 99.51%, respectively. A turbidity meter was calibrated with a TDS meter. The error and the accuracy values for the ultrasonic sensor were 0,53% and 99,47%, respectively. The system was able to read and display data as well as provide output with a response time for the water draining and filling system of 6,3s and 0,14s. The system built performed well in monitoring and controlling pH and turbidity in an aquarium.]]>
