Thanks mate 12' has A consensus apparently, maybe start at 14' and see if its ok then go down 2'.I have one and it's possible to go as close as 10-12 inches. It is only a 315w we are talking about. A 630 would need more.
Another factor to consider is the area you are trying to light up. If it's a 3 x 3 then adjust your shade so that there is a reasonable intensity of light out near the wall. It won't be as intense as the center unless you have the perfect shade, but you don't want too big a difference between the two or your central branches will leave the outside behind.Thanks mate 12' has A consensus apparently, maybe start at 14' and see if its ok then go down 2'.
I feel it's a bit strain dependant,have been running a lot of sats lately and they seem to be able to take that intensity with no issues