Green Birdsnest lost colour, but not bleached
 

I've had a Green Birdsnest frag for about 3 months now, and was experiencing good growth and polyp extension. I previously had 2 Hydor Koralia Nano powerheads for circulation, I just upgraded to a pair of the Tunze 6015's to improve flow. For some unknown reason, the Green Birdsnest polyps have lost all their colour and have gone white. It still has full polyp extension, just no colour. Everything else in the tank is doing well and has good growth and polyp extension.

Has anyone experienced this phenomena before? Will the colour come back?

I originally thought it was getting bleached, but it has been in the same spot for the whole 3 months. I've just moved it to the other side of the tank to see if it helps. It is still getting full polyp extension in it's new spot, but still no colour.

I'm running 2 Vertex Illumilux 12" LED modules (Marino Bianco) and 2 Ecoxotic Blue Stunners for moonlight.

Water parameters are good, as I do 25% water changes about twice a week and am experiencing good growth with all other corals.

Are they "white" white or more silvery? Can you see any brown on the skin?

It seems everytime inrebuild or make a major change my birdsnest gets ****ed and the polyps go silver/white but the skeleton is still brown. Colour comes back in anfew weeks once it's no longer stressed. Birdsnests are pretty tough to kill sonlong as they aren't receding.

Got a pic?

Check your phosphate levels.

Mine died when my phosphates went up. No idea what caused it but I upgraded to a bigger skimmer and added a media reactor with rowa-phos. No problems now.

Sorry no pic at the moment.

The skeleton is white also, the weird thing is that it is still getting full polyp extension.

Ca, Mg, DKH????

For filtration I'm running:
Live Rock
inTank Media Basket with filter floss, Chemi-Pure Elite, Purigen
AquaticLife 115 Skimmer
I am also using RowaPhos before the main pump.

PLUS, I do water changes twice a week.