Yeah GreenAcres, I'm not sure of the math myself. I was always skipping out to burn one during math class so...
. the info I got was off the Cannabis Culture forum web site. Just search for a "lumen calculator" and you should find it. You take the stated lumen output of the bulb and do some calculations based on the distance from the plant in inches. Anyway, my figure, based on the stated lumen output of the bulbs, was pretty high, and seemed too good to be true. That being said, I wasn't sure if I could get a tight bud with the cfl's, but I'm a week or two from harvest and they seem to be doing well (except for the heat issue which has caused some stress...). I really won't know until I harvest, but I would stay with my cfl fixture if it weren't a lot easier to vent a HPS cool tube or something like that. I've ended up with a lot of fans ( and wattage, more than 400w!) and it's still marginal for getting the heat out.
Boss has had to deal with the heat as well and he's worked out some good calculations for watts v. heat with the cfls. Sometimes the smaller wattage bulbs are better in that respect.
Peace
