LED grow lights experience?

[EarlyPan]

Regarding growing under LED's it's important to remember that with light, light of any type, the intensity on a surface varies inversely with the square of the distance. That means that if a lamp gives you a given number of lumens on a leaf at a distance of one foot and you double the distance to two feet the lumens will decrease by a factor of four. It's also difficult to compare light of different lamps, even two different color LED's, because of difference is spectrums.