Well........... I just had one of those DUH moments.............. I just realized that my nutrient solution is not strong enough! You see, I've been wondering why my plants, though obviously quite healthy, are lighter green than the others I see here. Not knowing what their natural coloring is, I just assumed they were one of those strains that tend to be light green. I was thinking thinking about a comment I'd made in another post, about the key to the best grow is balance: The right pot, with the right medium, feed at the optimal mixture, when you have powerful lighting! Then it dawned on me, I'm doing this test of this light, and plan similar lights to replace all my other lighting. Why? My auto pots taught me that my system had exceeded my lights abilities. My plants at only 600 - 650 ppms were dark green, looking in fact, borderline N toxic. I like running moderate ppm levels in coco, and have done so with success. BUT, this light is SO much more powerful than what I had, I just realized I'm going to have to raise the nutrient levels. I've been running super low, 475 ppms, so I'm going to go to 650 ppms and see if there is a change.