co2 mistery

If it's one thing i have learned in life, it is this, ask a whole bunch of people the exact same question in the exact same way, and the answer with the highest average stands at the very least a 99% chance of being the right answer, That being my reasoning, I will ask this Question one more time, not because I have asked the ? B-4 butt because I C Alot of posted forums on this very topic, and have read answers which have confused me even more, for it almost seemed that all of the answers or lets say oppinions were different some were similar but all different, so I start to think either nobody knows what the fuck there talking about, all of those who had similar answers had not been asked the ? in the right way, so with all that in mind I dare ask this simple ? about CO2.
TWO PART ?

PART 1
Veging stage---------Do you need it? if answer yes than Y?
Flowering Stage--------------Do you need it? and if yes Y and for how long?

PART 2
(this is actually an extra credit ? for the "gurus"

In an area aprox. 3x2x4 with moderate ventilation and only 1 plant is additional co2 needed or can it get enough from the air, and if not would a simple burning candle burning in the enclosed area be enough ?. if indeed a candle releases co2 (I always thought yellow candle meant carbon menoxide not dioxide)

..ok brother ill let ya know what i know...plants can use co2 all the time except at night...the plants needs the co2 more in flowering an more so towards the last few weeks of the plants cycle...also for your aera i would suggest the homemade co2 in a jug versus the candel..i hate open flames even from propane genarators....but once again as i always say if useing co2 make sure get a meter do not overpump..overpumping will kill your plants then you....peace