@ZenMan Thanks. I just wondered, as I had seen it mentioned, about the eventual decrease in lumens, or something to that effect. I guess if was all that much loss in effectiveness, you would notice a decrease in your plants, from when you first started growing under lights, as compared to now. I would imagine, the expense of some spectrometer, or other such light measuring devices would be more costly than just buying some new light bulbs! I suppose the whole idea, was about exposure to "red" light, but ultimately, for the plants, isn't it more about exposure to Ultraviolet light, from the sun? I know there is UVA & UVB , rays. But I do think that exposing seeds to sunlight, can help those that need it to germinate, while others actually require darkness.
