Growdude said:
6 x 90,000 = 540,000 lumens.
Hey there Albi,
Go with GD's advice. Six 600w HPS lamps is definitely the right way to go. That's actually a bare minimum for a 10x12 flower room. If you divide 3600w by 120 sq/ft, you get 30w per sq ft, which is a bare minimum and hardly an ideal lighting situation.
However, when you factor into it the centre isle between the two sides of the room, that you need to leave open for walking and working in, then your actual growing area is 120 sq/ft minus the middle walk-way which should be about 2.0 feet wide, at least.
So your actual grow area will be more like 4' x 12' on each side of the room, or 8' x 12' in total, for 96 sq. ft.; 3600w/96 sq. ft. = 37.5w per sq. ft. That is actually on the low side, but it will be sufficient for good yields if you plan to focus mainly upon pure indicas, and some largely indica dominant strains; but it is far from ideal.
Now, these are your options. First, instead of six lamps, go with eight 600 watters, 4 on each side of the room. The advantage of this over going with six 1000w lamps is that it provides a better spread and more even distribution of the light along each side of the room. 8x600w = 4800w total, or 50w per sq. ft, when divided by 96; and 7500 lum per sq. foot, which is closer to ideal, for maximum yields.
Your second option is to stay with six lamps but bump up the wattage to 1000w each, for a total of 6000w, or 900,000 lum; 6000w / 96sq/ft = 62.5w per sq/ft. ; 900,000 lumens divided by 96 sq. ft. = 9375 lum per sq. foot. This plan is even better, but is not without some negatives. Eight lamps will provide a better and more even light distribution throughout each side of the room; and you'll not be able to realize the full potential of this wattage without a sophisticated CO2 system and optimization of all other growth factors.
The third option, if you wish to stick with the six 600w HPS bulbs, is to reduce your actual growing area to 63 sq. feet, by locating it in the centre of the room and leaving a 1.5 foot walkway around the entire outside perimetre of the garden; 1.5 feet of walkway on each side of the garden will leave you with an actual grow area of about 7' x 9', or 63 sq. feet.
Now, 3600w/63 sq ft = 57w per sq. foot; and 540,000 lumens divided by 63 = 8571.42 lumens per sq. foot. That is fairly ideal and will be more than sufficient wattage / lumens for almost anything you'll ever want to grow, unless you're a real pure sativa freak; but even then, most pure sativas will perform well enough under those conditions when all the other growth factors are optimized.
Sorry to complicate the crap out of it for you, but dem's the hard facts, bro'! If it was me, seeing this is your first set-up, I would be heavily inclined to opt for the third and last option, of the 63 sq. ft. grow area in the centre of the room. Once you've run that a few times, if you feel it's inadequate, you can always split the garden in two later, move it to the sides of the room, and install two more 600w HPS bulbs.
Good luck with everything!
RT
