Need Some Help With Inline Fan

Okay, so I just bought a 400 Watt HPS for my second grow. My first grow, I used CFLs for both Veg and Flowering and I had a heater running 24/7 to keep temps warm enough. I did not expect to have heat problems till the weather got a lot warmer. My closet is in my basement which is around 60 degrees right now. Cooler at night. Well, that one HPS brought my temps to over 100 degrees! So, the Autos I needed to put in my Flower area (I have 3 Wild Roses and a Mekong High in veg) I currently, have under a 125 Watt CFL. They are only 2 weeks old, so I guess that's okay for now.
But, I need to get an inline fan. I have been reading about putting it on my reflector, but it seems like some people say blow cool air in and others say vent the hot air out. Let me know what you guys do! Please, a little advice is really needed!
+rep for replies!
Also, I have an intake and exhaust fan currently running and a humidifier with fan as well as an oscillating fan for each area. My current intake fan has a switch that can make it exhaust instead, so I could do a passive intake and run two exhaust fans if that would help! Thanks!

so if i understand your posting correct then you need to suck the air out.have it toward the top and it will vent all that nasty air out.bringin air in wont necesarily mae the temps drop just pushin the air around the closet. this is assuming you already have an intae fan thats important too.to constantly have fresh air as your pulling out dirty air

I do have an intake fan. It is in the center of my closet in the ceiling. I also have an exhaust fan. And 3 fans for air movement and strengthening the stems. I wanted to pull the hot air from the light out of the room, but a lot of stuff I read says it's easier for the fan to push cool air in. So, I'm a little confused on which way to set it up. Also, I have to order the optional glass for my light. +rep for your reply! Thanks much.

It's more efficient for the fans to act as a vacuum and allows them to move more air.

Setting it up to be a passive intake would be the best way to go.

i see what you mean, so you have air cooled hoods. they work either way i use them and i push air though it because i have 6 lights and got a inline booster in the middle to help it all go through smoothly.i didnt suck it out as vacuum because my ducting was in the attic and i didnt want to bring in the same air as i was blowing out through my other inline fans. but either way will be fine. you are only running it through one light so it doesnt really matter as long as your ducting runs out of that room, that air will never touch your closet

So, if I set it up as a passive intake, I just unscrew the panel, install the fan then ducting to the other side and out of the room. Then, I just plug it in and that's it?

oh so i see, your trying to suc air out through that hood also. yeah that will work i dont know about mounting the inline to the hood though, i would mount it somwhere on the wall and have a short ducting into the hood so all that weight isnt on your hood? becaause i now my inline weigh quite a bit. they air from active air. i dont know which one your running though so i cant really say

also a 20 dollar fan controller works great if you have problems with it lowering your humidity or if it just is sucking too much air out

My humidity is already too low. A second humidifier is next on the list once my light is operational. Underneath all the Mylar, the closet is cedar, so it absorbs moisture like crazy!