Cooltube ventilation.

Hi all!

I have recently bought a cooltube for my grow box because I desperately wanted to eliminate the use of a oscillating fan (just takes up too much space in my small cab). Without it, the temperatures rise to even 45C/113F (!) with the use of a 250W HPS.

Now I hooked everything up, tried to eliminate all unnecessary bends in the ducting and, Roberts your mothers brother, I finally had it hooked up and running... although the problem is that it brings the temps down to 30C... I was a little bit dissapointed so I just wanted to ask if the culprit would be my extraction fan. As of this moment the setup is like this cooltube -->ducting -->fan -->out of the box.

Now I bet this is the problem, because it's just a small poxy 110m3/h or 65 cfm fan. So I was wondering if my problem would be solved if I just bought a larger fan (it's about time to get a proper one) say 440m3/h or 260 cfm.

Would that suffice and bring the temperatures down or maybe ditch the new fan and doo something else? I've never had anything to do with cooltubes...

Thank you for your help and suggestions.

Now I've seen people with such a setup: air from the growroom -->ducting--> cooltube--> ducting --> fan.

But I've also seen stups like mine, pulling air directly from the grow box, so I assume both work the same, only the first being a little more efficient.

By the way, the air coming into the grow box is constantly cold-ish. I make sure that it doesn't get hot in the room.

Or maybe it would be just fine if I got a 130cfm fan? That's double my one at the moment.