Temps

I've read a lot about different temps hot and cold, but with winter coming and drawing fresh air from outside, what temp should I keep it above for optimal growth?

The "optimal" temps are anywhere between 72-79 degrees. During lights off, it's ok for your temps to drop into the 60's (some people feel that a 15 degree swing is actually good for plants).

75 is in my opinion optimal with a drop into the 50s during flowering sometimes being beneficial if you want any purple coloring.

So somewhere in mid 60's lights off and mid 70's lights on? I'm in veg now, is it same for veg and flowering? And I have read a couple things that corolate low temps to purple coloring, but is purely aesthetic as far as I know, I'm looking for optimal growth during veg and flowering, anything to cut time off veg and flower is good! Plus I want the best my plants can offer