I was hoping for a link with new info. 1000w in a 4x4 is 62 watts per sq. ft. That is in the intensity range in books about this. 45-50w is considered minimum for our plant for good results. I run 600’s over a 3.5’x3.5’ range and have no need for co2 added. And of course this is all with single ended hps. More usable light from a more efficient source would lower the wattage needed.