I just switched to a similar setup. I had a single 13W spiral fluro in a clamp light over the other side of my tank and my Brom (a small pup) just started producing the red. I just switched two days ago and the red is still progressing. So I guess it is enough light to keep it if its enough light to produce it.
i am now using t8 with 6500k daylight deluxe bulbs at 32 watts i am seeing a little red but was wondering does it get red slowly? and does it take long to root. i have it in spaghum moss in drilled hole in cork but not tied in just in the hole the moss i had really wet but now changed it and am not spraying it as much but the tips are folded under just a bit .leaves are a little on the hard side so i didn't know if it was dying or what.