Well of course the 1kw will have a better total yield and more heat but most likely at a less GPW due to less efficient bulbs then the 600's. Imo a 600 is good enough for a 4x2, anymore and your going a little overboard unless you have cuts that gain plenty from the extra light
If heat is a concern and you are not going to invest in a portable AC unit, then go with the 600. I have a 1000 dimable ballast that goes 1000/ 750/ 600. I grow in my crawl space with a ceiling that is only 46 inches high. I Scrog all my grows. The difference in heat between the 1000 and 600 in at least 10 degrees. I also have had issues with light burn on my center colas of my Scrog because I ran the 1000 almost the whole time. However I have kept my temps no higher than 80. I have rock hard buds and a good yield, but if you don't control the heat that will cause fluffy nuts with a 100 watt or 600 watt.
Get the 600,picky plants will hate 1kw in such a small area. use 8" intake/exhaust with a sealed hood and run your ventilation in an efficient order with a good inline fan, you shouldn't have issues.
You have a 8 inch fan and it only moves 300 CFM? That is very low for a fan that size. I have a 6 inch one that moves 430 CFM.
That should be plenty
8" dual active ventilated for hood and room intake/exhaust with some kind of hydrofarm 8" inline fan i forgot the cfm, wasnt much i think its 300/400 cfm idk
Depends on the type of fixture. 1000w Gavitas (all duel ended, regular or digital ballasts are as you say 600w more efficient) are more efficient than the 600w versions - however that's too much light for his setup. I think the 600 digital is a pretty reasonable choice. I think COB LED would be even better given his temperature concerns but the price might kill it as an option.
Yeah didn't think of that lol, his budget is 1k and that seems a little tight trying to pull a pound per plant, he will need to do some type of perpetual grow with some veg time and just keep the ball rolling till he's done
