Different makers have different lumen ratings, and also I noticed some say 100w or 150w equivalent but are different actual wattages(23-26w, 40 & 42w). I have one cfl growing 4 plants in a 4sq foot box right now, 3 budding autoflowers and a kushberry potential mom under 24/0 with a 200w(600w equivalent) 2700K cfl that puts out 12,000 lumens. I keep the tops within 2" of the light because it really doesn't penetrate more than maybe 8" too effectively.