Add to ORKGThis bachelor‘s thesis deals with design of automatic aquarium control system, equipped with microcontroller AT89C51ED2 and simple user interface. After opening introduction to systems, usually used for aquarium automation, there is described design of such device. First, it is selection of components and concept of their electrical connections. Next part is devoted to realisation and found problems and their removing. The last part is devoted to design and creation of program equipment of the control system. This part shows basic principles of control program and structure of it’s main parts. Low-level functions for communication with peripheral devices are also described