help with cooltube

I was helping a friend setup a growtent today "homebox xl" with a 400cfm fan attached to a 600 watt cooltube bringing air from outside through the light and out of the room the tent is in. Now the temps with it setup like that are hitting 83-85 so I decided just for hahas to take the intake side off the cooltube and see if there would be a diff if any,and to my surprise temps fell down to 75-78! I don't see how venting the tent through the cooltube would run cooler than taking fresh cool air "47 degrees btw" from outside makes for hotter running room? kind of defeats the purpose of a cooltube everything is clamped tight and once overed with aluminum tape so leaks are out.... anyone have a idea as to fix the problem?

its more than likely pulling the radiant heat out of the grow tent

Maybe its sucking the hot air of the tent through the cooltube and then exhausting it outside the tent. I'm just guessing pushing air through a tube isn't going to lower the temps, the room itself needs to be vented too.

randk21 said:

Maybe its sucking the hot air of the tent through the cooltube and then exhausting it outside the tent. I'm just guessing pushing air through a tube isn't going to lower the temps, the room itself needs to be vented too.

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I ve used a cooltube many times. I love them i always sucked air out. i wouldnt blow it out. but u could be sucking the outside air right back in. get an inline duct fan to help blow out the other air. or one to blow air in better.