Indoors during the summer I use CFL's. (growth stage)
Indoors during the winter I use a 400w HPS. (full spectrum)

Outdoors in the flowering shed I use a 1000w HPS year round, and suppliment with a 400w HPS during the winter.

Don't kill yourself with the gas. (suffocation) It's not worth it. And since plants grow just fine without the supplimental CO2, it is unnecessary except for a few specific cases. And if growing for your own meds, why add to your costs unnecessarily?

Extreme cold is fatal regardless of the CO2 levels. Get a heater for the winter nights and really cold days. An oil-filled one is good, because it doesn't radiate light every time the element comes on.

Unless your grow closet is air-tight...if you vent the heat out, fresh air will be sucked-in through the cracks and openings. There should be no need for an intake fan if you've got a working exhaust fan. You'll still need a circulation fan though. My exhaust vents are near the top of my closets, because that's where the heat goes. In the winter, I close the vents a tad to retain SOME heat, but still allows some air exchange. (fresh CO2)
Rusty Trichome Reviewed by Rusty Trichome on . need advice on intake air tempt control I am building an 8x10 grow room- that will be the floor deminsions- ceiling height 8' at lowest- I plan on making an 18" flat area atop sides with an a-frame dome at the 18" area angled up 2" to a 12" flat surface- I am building inside a barn loft and have extra height- to use as hood to collect and remove outake air- i can have intake air either coming into side or thru the flooring? this palce gets hot in summer and cold in winter- I plan on first grow being winter-How do I control the Rating: 5