I saw a 1000 watt HPS 8 inches above a canopy of 12 INDICAS (about 20 inches tall.
The HOOD was cooled with an exhast fan that was PULLING the HEAT AWAY...
But not taking the air it out of the room completely..

The plants were 7 weeks into flowering.... There was not a plant in the bunch that did not have a 28 GRAM(1 ounce) MAIN cola... as big as a childs forearm..

CLOSER is better...

THEY were NOT using CO2

If your mind has thoughts without your awareness.. you are unconcious.

LOVE