Quote Originally Posted by Mr. Clandestine
Hey chief, welcome to the boards! :jointsmile:

Having a decent intake and extraction method in place would be a good idea if you're going to be running an HID up there. If you can only afford to run one, I'd look into setting up a good active exhaust and maybe finding ways to setup a passive intake. You also need to remember that having all this equipment set up in an attic may take things from too cold, to too warm pretty quickly.

Get yourself a decent thermometer up there. You want to keep daytime temperatures preferably under 81 degrees F, and no higher than 85F if you can help it. Depending on several factors, temps above 85 might stifle growth. Also, having a quality ventilation system in place, you should be able to prevent the temperatures from dropping more than 15 degrees with the lights off. Big temperature fluctuations can lead to stretching, as well as a few other unwanted maladies.

Something to consider when running HIDs, you'll want to spend roughly the same amount of money on ventilation that you did on the light itself. You can prevent a lot of problems this way. Take care!
Perfectly put :thumbsup: