Quote Originally Posted by Cyclonite
I only used the cool tube with the end open and a passive intake....I havent tried hooking up the open end yet with the passive intake to see what temps are....if its only 10 degrees with a cool tube that would be great...what about 2 600s....I have a superfan if need be would that make them much more effective its like 1000cfm
Cyclonite,

First, if you want to use CO2, you need to get everything else squared away.

You should cool your lights properly; 6" air inlet to 6" ducting to your cool tubes more 6" ducting to your fan (265 cfm is fine for 1000w or 2- 600w) the duct to a 6" outlet. All of this should be air tight so it does not pull air from the grow area. Your exhaust fan should be separate and a passive air inlet is fine, just use an inlet damper (round, 4" is common size used for dryer vents) set so that air can flow in when exhaust fan is on and closes when not on. Helps keep CO2 inplace.

My 10 degree rise over ambient may be a little optimistic. If the cab is located in a living area I would assume an outside the cab temp of about 72degrees F. I would expect a cab of your size with 1000 to 1200watts to rise 15-20 degrees, so were looking at 87-92. Starting to get a little high but very workable with CO2.
(my partner and I are cooling 2- 1000w lights, with 400+ cfm fan, but the ambient air outside the grow room is currently 45 dgrees, the duct work is so cold there is a condensation problem on the duct work).

BTW while a super fan of 1000cfm will work it is no better then a proper sized one, you can only cool the lights so far, about ambient temp. The heat that builds up in the cab from the light is the radiant or reflected energy of the light.

On an other thread (damn I wish I knew how to link it, I suck at this computer shit) I answered dodo's question about CO2 and I rattled on about the various methods (and safety) of CO2, try to check it out.