What is wrong with my montipora?

[pat_ask08]

I recently purchased a small montipora from my LFS. The past week, it started turning green in the center and just keeps spreading. I use RO/DI water and I just did a water change 2 days ago. Nitrates are <5, same with nitrates, PH is 8.3. I have it toward the middle of my tank with medium water flow. My lights are a 4 bulb aquatic life.

 

[mr_X]

It looks like it's dying in the center and algae is growing on it.

 

[pat_ask08]

The past couple weeks, I've been having problems with hair algae but my blue leg crabs and emerald crabs seem to have taken care of most of it. Is there anything I can do to keep it from dying?

 

[mr_X]

You can frag it. That might stop the tissue death. Break the dead part off, leaving some of the live part with it, so that you have absolutely no dead part with your remaining frag. Then separate all 3 pieces to different parts of the tank (this will help you rule out a placement issue).