An inch or two at most..
CFLs work great but they lack Penetration, hence you have to keep them uber close..
Can be a pita once they start growing as you might have to move them daily ..
Seedlings don't have to be that close to the bulb, especially a hot 125W.. it might stress the seedling. I keep my seedlings 3-4 inches away until they are 2 weeks old atleast, and then I move them closer.