Temps in Flower with Co2?

There's really no good science on this subject. A lot of people want to mimic nature as much as possible but there's nothing other than anecdotal evidence to show that this is effective. The same people trying to mimic nature have no problem with 18hrs of "daylight" for example. Sometimes we can do better than nature. Cool temps supposedly produce more terpenes, which can make your flowers more tasty. This again is largely based on anecdotal evidence, but it is more widely accepted by growers. Cooler temps will bring out more color change if the genes are there. That one has a fairly good amount of evidence to support it. In the end, go with your gut and don't be afraid to experiment!