To maintain the pink it requires a lot of light. I have vibrant pink Birdsnest here that I have had culturing in tank for well over 3 yrs and in lower light it starts to go green.
I have seen coral farms from 2 meters deep to 5 - 8 meters deep. The reason for deeper farms is to prevent damage from storm surge and cyclones.
If you want to check out Walt's Coral farm here is a link to his website. Lots of cool pics!!!
http://www.waltsmith.com/Aquaculture/CoralFarming.htm
Cheers,
Tim