EDIT TO OP: I have to thank everyone who has contributed information, and have now refined what is needed to be automated in the system.
Automation of the feeder: An Archimedes-Screw on a servo motor set to spin for 1 second and then shut off for 4 hours. (Thank you Chagrin)
Automation of PH testing: Using an electronic PH tester to check for PH drift and changes once per hour and report to a Linux PC. (Once again, thank you Chagrin and Focalist)
Automation of Lighting: Upon entrance to the greenhouse, the room lights to allow for the grower to see should be activated, simple t5 tubes (aprox. amount of tubes: 2-4) The system will use red and blue spectrum LEDs as a constant light source to grow the plants and will not need automation (Thank you Focalist, I've decided the inbound usage of new LEDs outweighs the cost of HID) Finally, the fish tanks will be lit by T5 lights as well, and will not be automated.
Automation of Overflow: Using either a moisture content sensor (Chagrin thank you) or a microswitch sensor (you guys are really good you know that?) to detect water overflow and make a warning in the report file on the PC.
LIGHTS: http://www.sparkfun.com/products/9979 http://www.sparkfun.com/products/9983 ATTENTION: I'm looking for ORANGE spectrum LED lights as well. And would like to have all three spectrums in high wattage capacity.
ORIGINAL POST: I've been suddenly dropped with the challenge of automating an aquaponics system to do the following:
Activate 2-6 standard grow lights via system clock time control from 4am-11pm (On at 4 off at 11)
Activate an Archimedes-Screw every 4 hours (Basically just need to make a servo turn 30* every 4 hours.)
Monitor and report PH levels (Water acidity, usually done by electronic PH monitors, but requires the person to be there, this needs to be able to report to a computer)
Monitor and report for overflow (I'm thinking a distance sensor inside an overflow pipe, to monitor for passing water or debris, if you can think of a simpler solution, feel free to pass it on.)
Monitor and report pump activity to ensure it's on and functioning. (not necessary, but would be nice for the associate)
As of now this is a PROOF OF CONCEPT, and I simply need to understand the process, parts used, and coding behind it. If anyone is so kind as to help, I will be very grateful. The current machine I am going to be doing the programming, monitoring, and controlling from will be a simple standalone PC running Ubuntu 11.04 with the Arduino IDE program installed.
Thank you for your time, and please, if you have any other questions on this that need answering to help, feel free to message me or leave a comment below.