Hello all... I found this surfing the web and wanted to share it with you..
Air handling for an indoor garden can take several forms. General ventilation to provide air for plants, forced air cooling to exhaust heat from a HID light, and air conditioning such as an ozone or negative ion generator.
Caption for picture: A commercial grade blower pulls hot, moist air from the top of the space and exhausts it outside. Air enters from a large opening in the bottom of the space. Note that no air cam be exhausted from an airtight space, and too small an air inlet restricts the amount of air exhausted by the blower. Since the blower is only sized to provide fresh air for the plants, it runs continually whenever the light is on. An oscillating fan keeps the air among the plants fresh. A surge strip is plugged into the light timer, protecting the light from voltage surges and allows one timer to control the light, exhaust fan and oscillating fan. The ballast is set off the floor in case water is spilled.