sps question, what would you do?

[chwkreefer]

I have a small montipora cap (3.5" dia). I have had it for about 7 months. It has been growing well but I noticed that over the last week or so that one small area on the original part of the frag is getting some brown algae on it and it appears to be bleaching out abit. Now the area is about 3/4" X +/- 3/8"

This area has spread abit, be it all very slowly and I am concerned about what I should do. Should I cut that area out or just brush the area to keep the algae off and see if the zooanthellae will repopulate the area. I don't know what has happened to it. Something obviously irritated that area. All my other SPS look great.

If you want to know some specs on my tank. It is a 72 gallon about 30 sps frags and another 20 various species of softies and LPS.

Calcium 430
Alk 3.8 Meq/l
pH - fine
Nitrate ~1.0
P04 undetectable

Lighting 2-175 watt 10K MH
2 NO 40 watt actinic
2 NO 40 watt daylight
Lots of various flow with powerheads on timers

Any thoughts would be appreciated
Bill