Heat is something everyone needs to deal with. Glass heat shelds on the HID light and air cooled will help a lot.

When you use CO² its best to have the temperature in the mid 80's. The extra heat will help the plant to absorb the extra CO²

There is an FAQ on CO² basic you should have a look at.
Zandor Reviewed by Zandor on . Homemade growbox Hello Mr. Obvious.....Long time reader.....First time poster... This is my first grow in a LONG time. My grow box is a homemade from plywood with dims of 8ft X 4ft X 4ft. Ventilation consists of 4 24VDC electronic fans, 1 stand alone fan and a small exhaust fan with a built in carbon filter. Cabinet is subdivided into a Veg chamber and a Flower chamber. Lights - Veg...150W CFL Flower....400 W HPS Nutes - MG in very sparse quantities plus good ole Superthrive! All plants have been Rating: 5