Fan size question

Hi I'll be growing a scrog of 4 in a 1.2x1.2x2m tent and I've been exploring a lot of options to make a cheap intake and out take as I'm on a tight budget but as a fallback I was wondering what's the minimum fan size I'd be looking at to keep things running smoothly?

I'd go with a 6inch, too much heat will ruin the life span of your bulbs, make the weed smell travel farther, and if the heats too high you could get less potent/dense nugs(varying on the strain(even hermies if its too hot)). The 4" is only like 20bucks cheaper, so I'd put that 20bucks in for the 6" to make my grow room suitable for higher wattage bulbs in the future. By 6inch I mean exhaust fan, you want to also throw in regular cirulating fans to keep the air moving.

As for intake, booster fans work well if you dont have long runs of ducting. Are you running a inline exhaust fan? If not, i would dump my money in one, get double the fan you need, using passive intakes. Since your scrogging the plant will block some airflow, a nice vertical fan in the corner would move air through the dense foliage. Also, as Marlboro said, go with the 6 inch. Four was not enough for me.

I would agree with Marlboro47 I've got the same size tent as you, I started off with a 4" TT which was rubbish and replaced it with a 5" RVK which was better but wish I'd gone to the 6". I now use the 4" as an intake fan as well as a couple of fans in the tent to move the air about.