even more grow tent questions

Ok, I'm considering an 8' x 5' tent. (2) 1000w hps daisy-chained together with duct work running from outside to outside.

Issues:
The tents only have 6" vent holes so I assume that I need the most badass 6" inline fan that I can find. In fact, is there one bad enough to cool two 1000's?

Also, these tents are 78" tall....that only leaves me about 4" at the top of the tent to rig up something to get the heat out and keep air moving. I know I should be sucking air out but I don't know if space will allow a fan on top...in fact, it probably won't. Would blowing air in at the bottom and leaving all vents open at the top work?

Another question...How cold is too cold. It's gets pretty brutal in the winter here in Montana. Will pulling air that's below freezing through the lights and fixtures harm them? What about moisture...I suppose I can use a "down spout" as the outside inlet but what about moist air as when it's snowing? Would this moisture pop a bulb?

Thanks for any input.

1. You can get a duct reducer. 8inch to 6inch. Although a nice 6inch fan will probably suffice.
2. The tents usually have an opening at the top where you can place the fan outside the tent on the top of the tent, all you need to do it run your ducting in hook up your filter etc.
3. I dunno I don't pull outside air. But I don't think pulling sub-zero air into the tent would be a good thing.

3. My thought is that rapid temperature change would harm the bulb but very cold air won't since the temperature will drop to very cold gradually. Dunno though. I wouldn't want wet air hitting my bulb, and if moisture gathers on it that could cause a rapid temperature change.

Thanks for the replies.
I suppose I could intake room air, (stays in the low 70's), and exhaust it outside. I'm just trying to not buy everything twice.
Any opinion on the best 6" fan for something like this?
Thanks again guys.

Just find the best CFM number. My growbrights from HTG work fine. Check them out

Ok this is what you have to do.
Have your lights in cooltubes or hooded reflectors. Have your intake for the lights coming in from outside the tent and then going threw the lights and outside the tent or by a window.
Seal the tent off and controll the temps with dehums and a/c. Have one outtake on a humidistat that has a filter on it. Now since your tent is nice and sealed you are sappose to fill it full of co2 and buy an A/C that turns your outtake off so your co2 doesnt escape. A 4 inch fan will be enough for the tent and a 6 inch is good for the lights.
Run the lights outtake only when they are on and run the 4 inch the least you can while the lights are on and all the time when they are off to reduce humid air. you wll have to add an intake for the tent to replace the air the 4 inch pushes out. Add duct. That maximizes co2 in the tent because no air escapes.
If you dont run co2 then just suck the air out threw the lights 24/7. connect it a filter in the tent if you want to reduce smell and avoid getting busted.
Go buy a Portable a/c 3 in1 heater cooler and dehum. Get bottled co2 and good luck to you.

you can use a can fan 6" to cool both lights.
Each 1000W should have around 250-350CFM air flow. I used 2 6" air cooled lights inline before and used a 440CFM inline fan to blow them and it worked well. They do tend to get pretty loud.