I've been running one of the Mini 6500k from veg all the way through. The bulb is awesome, its lumen output is 9500 for 125w, and the dispersion of light is incredible. Worked real well in a large reflector dome, works even better just as is. Cause of the low heat, and high lumen output, I would do a an entire grow with 4 of these. I would use 2 6500k, 1 mixed 6500/2700k and 1 2700k for veg, and swap for flower. 2 2700k, 1 6500k and still the 1 mixed 6500/2700k. That would be 500w, 30,000 lumens. Still not as much lumens as a 400w hps or mh, but lots less heat, and since the lamps are all self ballasted, its is a true 500w draw for the cfl bulbs. Four of the lotus minis, I am talking about the mini bulbs, the standard lotus runs 200w and emits 15,000 lumens, four the minis could cover four plants through veg and into flower, and you might want some supplemental cfl or led bulbs placed where you feel. Looking at it, running three standard lotus bulbs is a true 600w draw, and emits 45,000 lumens, which is half that of the 600w hps, but the cfl spectrum is much more focused and tuned for photosynthesis, a lot less 'wasted' light spectrum. As for cost, the standard lotus is around $75 right now, so three of those would be $225 which is about the cost of what you need for a good hps. Four of the minis would be $160 which is about the cost of possibly well maintained, kindly used gear. So the value may be there, cause these lotus bulbs are cool enough to be 3 inches from any part of our girls. I have checked this and confirmed with a temp meter.
