If only PAR meters were cheaper and easier to find... *le sigh*
I made an irresponsible impulse buy of an ORA Green Birdsnest coral some time ago, even though I only have a 2 bulb 48" T5 HO
fixture. I couldn't resist. Bad John! Bad!
But, at about 6 inches below the surface with the bulbs another 3-4 inches up, the birdsnest is flourishing! Polyps so extended it looks fluffy, brilliant neon green, and I can't be sure without measuring, but it already looks bigger.
So, stick with medium light varieties like Montis and a few others, and you should be good. The Green Birdsnest is also a good choice. The 'normal' birdsnest needs more light, as I understand it.