like others said, u can run a 1k in 2x4.. as long u can control the heat.. problem is, that w/ nearly all rectangular tents, the Air cooled openings are on the wrong ends.. in yur 2x4, the bulb should be centered and orientated perpendicular to the long side, not parallel. It would take some clever ingenuity on yur part to make it air cooled, and you'd still need a nice exhaust fan anyway.
a 315 is just right for a 2x4. u can run it open air, as long as u have a small desk fan for circulation at plant top level, and above the lamp have a 400+ cfm vent fan.. attach a carbon filter and no light leaks..
It's been my experience that a 315 is not ideal for a 1 sq meter area .. i've found that it takes roughly 1 and half 315's to accurately cover a square meter.. That's three 315 lamps over every 2sq meters. To me, a 315 is equivalent to 450 or 500 watts, like somewhere in-between a 400/430 hps and a 600 hps, in what it will yield you, per m2.
. But 315's have their advantages, u can hang them much closer and they run cooler than a 600. Just know, that if your trying to calculate watts, a 315 will draw 350-390w from yur wall, not 315 watts. Even still, 1170w (390 x3) every two m2 is less than the 1300+ watts that a pair of 600's would be drawing.. It's been my experience that a single 315 does not have the coverage to crush a 3x3 like a 600 does, but a 315 outperforms a 400 or 430. In a tent with reflective walls, running plants wall-to-wall, the difference would be even more pronounced.
If u acquired one more tent, or something, u could start up rotations. Keep the autos in yur veg under 24/0, that will be like bonus weed inbetween yur 12/12 runs. a single 2x4 will feed two 3x3 tents..
