Its best to keep an extraction/exhaust fan running 24/7 for better air circulation
If ya turn off the exhaust/extraction fan in the dark period/lights off ya see a massive humidity spike & this can lead to powdery mildew & bud rot problems... ya really don't want that !
Can be observed with ones of those humdity reading gadgits tho, if its has low & high recording function to it or by reading the device before lights go off & just before lights come on
A tent that size will more likely require 2 X 600w bulbs for optimal coverage of lighting & that a 5" exhaust/extraction fan is below average... more likely aiming at a 8" inline fan...
However with just one 600w bulb or just the 2 X 250w bulbs for clones, ya more likely get away with it !
A large tent like that ya still looking at 2 X 600w bulbs & air cooled hoods would be a good option to control heat issue's if any do occur ?
As 600w bulb will roughly cover an area of 4' by 4' at best.
A 250 bulb will cover a 2' by 2' being pretty optimal.
This all depends on wattage of bulb divided by square foot coverage... thats a reasonable old school calculation which appears to hold true to present day but does not include the rule of the square law light effect over distance to diminshing returns of hanging height.
Optimal wattage per square foot is 65w, average 50w & just about get away with growing 30w this directly effects end yield when using HPS or what ever bulb type ya use for flowering tho...
Ultimately if you want to reduce over all head cost for vegging T5/T8 tubes of 6500/6400k will be pretty good... saves buying loads of ballests & a tad cheaper to run on electric than MH plus ballest...
