I will be purchasing a grow tent (76" x 76" x 76" - 6'3" x 6'3" x 6'3") and throwing up a 1000w lamp. I currently have a 6" inline and a 4" vortex with a 4" phresh filter. Would this be sufficient cooling (6" dedicated to hood, 4" for filtering/venting?) Or would I need a 6" fan/filter combo to vent this tent.
I personally think the 6" fan will be fine for the 1000W light, but I think you're going to be disappointed with the results from a 4" fan in an environment that is ~250ft^3, especially with a filter attached. I usually aim for turning over the air in a grow room at least twice a minute, which would mean you'd need a 500CFM fan (again, most CFM ratings are based on open flow!). How often you exchange the air in a room is subjective, but I do think a 4" fan just isn't going to be enough IMHO. It may work, but it won't be ideal. What are the fans you're using rated for in terms of CFM? Also, where are you venting the exhaust? Is it actually going outside, or is it being vented into whatever room the tent is in?
I use a 4" (170 cfm) fan for a 2x3x6 tent with a 400 watt HPS, its just about perfect. You may want to think about jumping to at least a 8" fan for your space.
I had a 6" vortex fan in my 4x4 tent and while it worked great for eliminating the odors. It did next to nothing to keep the temperatures in check. I ended up having to purchase a portable A/C unit to keep it cool.
Thanks for the input guys, I was primarily asking because I own a ActiveAir 6" (400cfm) and a Vortex 4" (270? CFM) paired with a Phresh filter. Someone asked and my exhaust goes a few different places, depending on the weather. More often than not I vent it under the house, but if its really cold, I blow it directly into the room the cab is in to warm it up a little. How about this idea - I put the 4" vortex on a duct reducer (6" to 4") and use that to cool the hood and purchase a new Phresh filter to fit the 6" fan? I'm trying to budget everything in - need the tent, 1000w HPS, Magnum XXXL hood, new beans and whatever ventilation pieces I need. Was hoping my current fans/filter would do an adequate job as I'm on a budget. In theory you only need to exchange the air once every 5 minutes. I know a 1000w lamp produce a lot of heat - but in a 6x6 area when most people stuff them in a 4x4? At exchanging the air once every 5 minutes, I'd only need 50 CFM - assuming the 6" fan cools the hood appropriately.