I have a little over seventeen thousand lumens in my closet grow. Two, four foot, two tube fluorescents and four cfl's. My golfing partner is using a t5ho with twenty thousand lumens. His grow is a week ahead of mine. My plants just turned a week old and I'm hoping the t5ho light I ordered comes in today because his plants at two weeks old are amazing. He is using a four tube four foot fixture. I researched the lights and a t5ho puts out more lumens than a metal halide 400w. I have eighteen plants in a space that is only fourteen inches wide. My light schedule is 12/12 right from the start. I'm trying to cut down on the veg state and basically have one main cola on each plant. I plan on keeping the four cfl's for extra light during flowering, however the t5 alone seems to be working fine for him. Hope that helps.