Birdsnest and nutrience

[Gills 619]

I have been using prodibio digest and optim for about ten weeks. My nutrience is low as the tank has cleaned up nice. All the corals are growing well and look good. Some have lost some colour and have gone more pastel, I guess due to the lower nutrience level. I feed the tank with Brightwell aminos and vita chem and the colour has improved. ( My clam also went pale ). The problem is the pink birdsnests are slowly SNT'ing. They have not recovered even after upping the feeding. Is the nutrience still to low for them or could I be looking in the wrong place. The clam has also regained its colour. My green birdsnest has lost all its brown and has a little green on the tips and the rest is white. Looks like bleaching but is at the bottom of the tank. PE is still exellent. Do the birdsnests require higher nutrience levels? All perameters are spot on and tested every week. ALK 8.5 CAL 450 Mg 1400 SG 1.024 Temp 24.5 to 26.6 *c