Imo 11,000 under the full spectrum is the high end for a seedling but should be fine.
Now I'm gonna go off and say something unpopular... for your benefit.... (see this??? Going out on a limb here to have my ass raked over the coals most likely)
So intensity is not why seedlings stretch and infact I have seen more seedlings under to much light intensity than I have seen under proper light intensity resulting in spoon many cases of stunting the plants and all sorts of other issues that lead them to chase ghosts.
Ok cars again for ya here.... TO LITTLE IS ALWAYS BETTER THAN TO MUCH. ITS NOT WORTH THE ABSOLUTELY NEGLIGENT INCREASE IN GROWTH TO RISK THE COST OF A HUUUUUGE LOSS OF GROWTH AND HEALTH. I have 2 times here EVER seedling stretch due to intensity and ill tell you why... both times the growers had the solo cups placed by the window as the only source of light.
ok survival kit in hand. Going forward here.
What causes seedlings to stretch?
1. Well genetics and contrary to most ppls idea of what stretch is in a seedling almost all of them I see are normal.
2. Spectrum... find a blue leaning spectrum for seedlings and they will stretch much less. Many prefer Florida tubes and I'd say anything above 4500k should be fine.
Why? They are not super intense like LED so much more forgiveness and they tend to lean much more to the blue side of the spectrum which will reduce internode spacing.