i mean this kid comes in here copy pasting shit off wikpedia, making abselutly no sense, and i dont want kids coming in here getting false information on lumans and light spectrum colors. its so stupid i told him to drop the whole matter because it was irrelavant and hes gone on to wikpedia thinking i know nothing. Any one whos taken a chemisty class knows this stuff with out a complicated explination. Lumens = power of light. Par = range of light plants use(visible light), which differs from veg and flower. But no one talks about PAR they reffer to it as the light spectrum. To answer your question in the beggining hagbard, if you want potency density and better maturation time, get a hid system. 20 cfls will not run cooler, maybe 5 of them will, but i have herd of people with cfls having problems with proper ventilation. plus instead of worring about one light burning your plant, you get worry about 10+. And to answer his question on par levels for cfls i belive cool white contains all levels of light, PAR. Warm white, contains more red spectrum, The higher par levels.