No please do not attempt to introduce co2 into your root zone ever. Not only is it useless to the plant, it goes into solution in water as carbonic acid and will royally screw your pH balance.
Atmosphere only, at temperatures high enough, with intense enough light that the plant can actually use it.
I only juice in flower, during 'daylight' hours, and only in the 80-85' range. You can run your room a little warmer if using co2, and if you have temperature control issues, this is a very good way to reduce stress on the plants. Set your tank solenoid on the same timed relay as your big lights, and run a thermostatic regulator so it releases gas only when temps are high enough, or you're just blowing money out your ventilation ducts.