Color Changing Coral

[blkhawk10]

I bought a red acro a couple weeks back and since it's been in my tank has turned green...why does that happen?

 

[Defect]

Could be not enough light or could be high nutrients.

Red planet is a great example of this happening. In lower light it turns green and in higher light it is red.

 

[blkhawk10]

I got a 150 watt metal halide with a tru lumen actinic but the builb is almost a year old so maybe that has something to do with it...I don't think it's high nutrients because everytime I check my phosphates and nitrates they are 0 and algae doesn't even grow in my fuge.