I agree with Antwan......sort of! LOL!
Buying the system similar to the one we are talking about can cost a lot of money however if you can do it yourself, it is much cheaper. The controller (PLC) costs me around $200cdn with software and the cables to connect to my computer. All I need to start doing is adding the parts I want like the solenoid valves, float valves, probes, sensors, etc, etc that I want. These can be easily found. These 'systems' are often used in factories/plants/industrial settings, not only in aquariums. Therefore, if you know where to start, you can get some amazing stuff.
http://www.omega.com/