I have the same CO2 Sensor, but on a 5v breakout board with an adjustable pot. I wanted to incorporate a fan speed controller, that circuit looks like it might just do the trick with the diac. Those openreef BNC boards look pretty good as well. On the to-do list is the following:
-Third on/off timer --> Interval timer: hours/mins/seconds ON hours/mins/seconds OFF
-Enable/Disable setpoints ----> Auto/Manual control - relays
-System --> Change username/password
-System --> Update interval --> based on time not number of loops.
-System --> Display versions [serial] ( ie. Arduino Firmware Version: x.x.x, Python yieldbuddy Version: x.x.x, PHP yieldbuddy Version: x.x.x )
-System --> Event Log (use SQL and date/timestamp)
-Email Alerts (System --> Email Setpoints --> Email Alert Enable/Disable)
-TFT LCD Screen
So far I have done the following:
**Fixed set arduino time under system
**Fixed RTC setup sketch to use DS1307RTC library
**Split sketch into seperate files
**Fixed relay buttons on overview.php into a table
**Removed lighting and watering pages and put them on a new timers page
I will post the new code soon.