Sinularia dura looking bad

[bromion]

I have a Sinularia dura that's been in my tank for over a year and a half (came with my first LR). It has been doing well all this time, but for the past 2 weeks (about) parts of it have been looking bad -- no polyp extension I can see, crusty-looking surface. All my water parameters are in line except a somewhat low alkalinity of 7.5. All of the other corals in the tank look normal.

One thing to note is that I have a fair amount of green hair algae. I've been trying to remove it slowly through siphoning and water changes.

Here are two pictures, hopefully these will help. (click them to see bigger size)

In this first one, you can see the left-most "horn" looks good, with polyps and a translucent pink color. The others have no polyps and look duller.
<a href="http://picasaweb.google.com/jasonm1/AquariumLife/photo#5060129994889755474"><img src="http://lh4.google.com/image/jasonm1/Rjkxa66z-1I/AAAAAAAAA5M/O8kk9H8vPFg/s400/R0011923.JPG" /></a>

This one is taken from a different viewpoint, where you can see the top surface of the coral better.
<a href="http://picasaweb.google.com/jasonm1/AquariumLife/photo#5060129831680998210"><img src="http://lh6.google.com/image/jasonm1/RjkxRa6z-0I/AAAAAAAAA5E/jioOe3dnU0k/s400/R0011924.JPG" /></a>

Thanks!
Jason

[FOSELONE]

hair algae...try some sea urchins...