I actually believe there is more to growing reds than just nutrients and the amount of light:
The spectrum of irradiance should also influence which shape and color plants might take. I speculate more blue light grows better reds - and red colors can be seen pronounced of course under a bulb with red peaks.
In pelmato's case I suppose the t8 reef sun combo of 50/50 6500K with actinic light intensifies the turning into reds very well whereas the flora sun with high levels of orange and red wave lengths helps in viewing the striking red coloring. Thanks pelmato for the shots!
I hope in a not too far distant future I might test that hypothesis myself while taking some pictures for proof.
Found this a moment ago which explains the viewing part of the topic quite nicely
James' Planted Tank - T5 Lighting On The Cheap