Wow, this looks amazing!!! For me - EtherMega and AtlasScientific shield+sensors are very expensive, so I will be looking for much cheaper solution. Standard Arduino 2560 with Wiznet5100 shield is as low as 12,50 USD and EC +pH sensors is in my (my friend) development right now.
Yes - this is something what I’m thinking about for some time. How to fully automate nutrients and water dosing with pH control, how to calculate amounts accordingly to barrel size, how to flush the system (for not mixnig old and newly mixed water)…how to dose and measure pH and EC properly (after mechanical mixing and wait some time?) …questions, questions everywhere 