Birdnest's weird lighting requirement!
 

Well I have two birdnests in my tank a green one and a tubs.

The green one has been at 10" in my tank and has been growing crazy. The polyps are very very well extended and I am not loosing color (found that the skeleton of this one is brown).

The tubs birdnest (purple polyp with green body) is around 15" in my tank (height from the bottom). When I had the two T5s; it's skeleton was turning green as it should be but then when I changed it to four T5s, it became brown :S

That obviously made me conclude two things: high nutrient (no) or less light (seriously?!).

So I did some searching and came to find out that green, purple, etc. (other than the pink one) colors up well in low light while the pink one needs high light! WEIRD!

Well that do makes sense since my light increased and the tubs is turning brown.

So hoping someone with tubs birdnest can chime in :)

Both of my birds nest colonies, brown w/purple polyps and white w/green polyps, turned bright colors and grow like crazy now without nutrients
Lots of GFO usage and they look great

I don't have tubs ( don't know what you mean ), but I've found the best results with my birdsnest that were brown was to reduce my tank's nutrients

Brown birdsnest usually means high nutrients ... HTH :question:

Tubs birdnest is the one you are referring to as brown with purple polyp :D

Well I also thought that it might be because of high nutrient but previously I did some searching about birdnest placement and found they prefer low light for better coloration :S

So did some searching and found that the brown will turn green if placed in low-medium light. Makes sense since it was in medium/low light before my light upgrade and it was green. Maybe you can move it to lower light to see what happens? ;)