Now I think that definately rings true for the 3watt diode LED's. But for my 5w diodes im really not so sure.
This info came in the box.
Mine is the 900W version...which says 2.5-3ft for seedling/veg and 3-3.5ft for flowering. Sort of seems counter intuitive that it lists a closer distance for veg than flower. Oh well.
Gotta go out and grab some chain this week probably get enough that i can hang them at 2ft/60cm from the top of the bucket.
Im guessing its pretty easy to recognise you're too close...for seedlings they'll probably wither and die and for plants the leaves will get burnt... definately don't want to hang too far away for optimum growth though. I have 2 900w lights and a light mover. I'm guessing it will be close to a month before 5 pots have spread enough to need more than one light on, and then longer again before they have spread enough to need both lights and the mover.