The filter does not cool down the room BUT the air that is extracted through the filter will be warm air so kinda yes. You want to draw the heat out and not just keep pumping air in, you cant just keep pumping air in or it will just circulate the warm air already inside.
I actually kept my ventilation/fans off @ night before and that was a mistake. Humidity shoots up and I read that any plants needs fresh air circulation @ all times. But PC fans arent really industrial stuff so :S
*Can't wait til I post some pix xD
I don't know why I had to sound like such a dick earlier, but window screen could be like $4.00 or something. (don't get the whole screen for the window, just the screen stuff.)
P.S. It would be very helpful for you to list how much space (cubic feet <- Americans call it that) and airflow you...
I'm on my first grow and I used half coco-grow and some fox farm seedling soil (started with a clone) so this stuff worked really nice and let the roots grow right into it. My clone didnt even go into major shock or anything when I transferred it from some generic soil to the part coco, part...
My grow supplier told me when leaves curl upward its due to over feeding and when its drooping down it could be several things, mainly over-watering or the humidity is too high. This isnt very serious because your plants look full of life without bug problems.
I wish I saw your set up right when you started it because I also have a PC grow and I'm about as far as you are (time frame). One thing I hear though is that plants can strangle each other @ the roots or something, so be sure to watch out for that. I'm a first time grower so everything I know...
Dude, dont be worried about the costs of window screen man. Last thing you want to skimp on is your filter. I used the "Filtrete" a filter they sell at hardware stores then split it in half then added the carbon.