The left duct is coming from a window on the side of the house that faces a wall - the space between the house and the wall is about 2 feet maybe. I started off using it as an exhaust - before I drill a hole into the ceiling of the closet to exhaust to the attic. Now, I draw cool air in from the outside and blow it on the bulb to keep temperatures in line (right now we're at 78.8 dF/26dC).

The right duct is coming from an A/C vent that has been covered except the duct and is blows into a small ventilation fan that blows a little above the plants to help make them dance a little.

If smell becomes a problem - I'm going to install a carbon filter near the ceiling between the left duct and the outside.