Venting a grow tent question...

I have purchased a Growlabs GL60 grow tent. I plan on purchasing a 400w hps cooltube to go with it. Will the fan/exhaust setup i have in this picture work for keeping the tent cool?

yes that will cool ur tent... as far as fresh air (co2), no...

I wouldn't recommend venting directly into your attic. (You can pull the fresh air in through your attic), but your going to have to have somewhere to push the air outside so it sounds like you are going to need a carbon filter or an ozone generator that can be placed in the outlet ducting.

You are going to want to pull the hot exhaust air out the top, and bring fresh air in on the bottom. I would pull air off the top, through the cool tube, and out. Or have an intake and exhaust specifically for the cooltube, run off the inline fan, and then a separate intake (low) and exhaust (high) for the plants. That would be your best bet. I find it hard to keep my tent cool with LEDs and CFLs.