like i said i dont know for sure but heard it..from talking to led makers.. i am not saying that leds are stonger then the sun; because nothing is stonger then the sun. but with leds you have spacfic wave lenghts and too much or a centin wave length can shut down chlorophyll. i think its the blue spec? but not sure and cant rember. the sun just give the right amount not to shut down chlorophyll, but leds can give too much and shut it down or slow it down. i guess its kinda like when you mix MH with hps at the same time, it slows down your plant and affects yeild. like i said i am not a led maker but was just saying what i heard, and stating why i dont want to add my other light to my grow right now.