Bleaching/dying red algae..help!

[SteveConn]

I bought some red halymedyia <sp> few weeks ago and now it looks like its dying in my sump. I initially had a crappy 3500K CFL lighting the sump (fine for the green algae), and have since updated it to cree white and royal blue LEDs. Lights are on 13h per day. My nitrates are undetectable and PO4 at 0.04ppm. Calcium and Alk are good for SPS
In the last week or two , the algae has been losing its color and is now pale... almost dead looking. It initially has grown, but now looks pretty awful..loose and pale, not the deep color it was initially.
Green algae is doing fine as ever. Too much nutrient competition?

Any advice?

Thanks

Steve