Great project and detailed write up from marjanovic_davor on instructables:
Motivation
My motivation for doing this instructable was to make life easier to all those aquaponics enthusiasts by automating the system so they can have a better control and monitoring of the system, and to allow them to experiment more easily with different settings to see which ones give best results.
Controler
The system uses Intel Edison as a brain, many thanks to Instructables and Intel for providing me with this nice piece of hardware. Controller is made to be plug and play, you just plug in regular aquarium water pump, lights, air pump and fan to the controller box and attach the sensors. Controller can be hidden somewhere as everything can be viewed and controlled in the webpage on the local area network. Webpage displays the sensor data and enable users to change system settings, sensor data is refreshed using websockets so it has a good response to system changes.
To control water flow through the gullies water pump(AC) and water flow sensor are used. When certain amount of water passes through the gullies system can pause for some time to allow better aeration of the roots. If the water flow stops (pipes clogging or water pump malfunction) an alarm is sounded with LED indicating what is the problem.
You can set which period of the day you want your plants to receive light (eg. 10am to 10pm), if the ambient light is strong enough “artificial” light will be turned off to save power and when ambient light drops under user defined value artificial light will be turned off. There is a second light sensor that measures system light, so if the system is not getting enough light even when the artificial light is on an alarm is sounded with LED indicating what is the problem.
Aeration pump can be turned on or off by system settings, and fan can be turned on if temperature goes over user defined value.
Alternating current circuit is completely isolated from the Intel Edison circuit by using 4 channel relay module with optocouplers.