As of right now here is the hardware breakdown.
pc for your software and datalogging
pc power supply for 5v, -5v, 12v, -12v, common ground(rev2 only needs +5v and +12v, common ground)
arduino mega
8 relay boards wired into a power tree using some stuff from homedepot(basically 220 dryer outlet<3con#10cable>load center> 4breakers>8relays>8 outlets)
Drivers:
1 relay>lights(have them all on a flower timer)
1 relay>exhaust(cooling) fan
1 relay>exchange fan +circulation fan
1 relay>ph doser
1 relay>pump
1 relay>o3 generator
1 relay>feeder solenoid
1 relay> fresh water fill solenoid
Sensors:
pH sensor board
ppm sensor board
4tempProbe/1humidity sensor board (1 in res, 1 in canopy, 1 in rootzone,1 general room)
co2 sensor
CT coil based energy draw sensor (still in dev but pretty much there)
The firmware on the arduino takes care of everything it has some default settings that can be configured via a few simple serial ASCII msg or the datalogging software I made(WPF, c# hehe) changes are saved in the EEPROM but I am going to add sd card or an external EEPROM/flash solution, I am also adding in lcd screen and button support for onboard interfacing. every 5 minutes the arduino sends "status" reports of the various sensor/relay states. Then it just follows my "program" of various timers and conditions, just needs a time sync everyonce in a while but I am adding an RTC which will keep it accurate enough for what we do.
I also love the fact for like 30 bucks you can have one serious bad ass cycle timer(small arduino, relay board, husky replacement power cord, catv cable)