Hey not sure about the light distance in flower with the photobio phantom mx 680w. I have it at 21 inches at the moment in early flower. I only have a lux meter at the moment. If anybody has this light and could show pictures of there grow and how far of a distance they used that'd help alot. I got a pound and a half off my mars hydro grow and put two tsw 2000s at 16 inches at 65k Lux. Pics are from my last grow.