PPEs turning colors, skirt shrinking

[fsn77]

I picked up a small frag of PPEs a couple of months ago. They've looked great and I can't wait for them to start putting out new polyps (none yet). About two weeks ago, they started changing color and the skirts started shrinking. Now, my PPEs have a ring of radiating green stripes that starts about 1/2 the distance between the mouth and the skirt and extends out to the skirt. The tentacles on the skirts have shrunk down to little nubs. The mouth is still green and the space between the mouth and the ring of green stripes is still purple. Sorry, I don't have a picture of this (tank is in my office, camera is at home) and my phone doesn't capture a good photo of them.

Would too much light or not enough light cause this, or is this indicative of some other issue?

The tank they are in has been running since December 2008, so while it's not particularly new, it hasn't really been running all that long. I use Oceanic salt mix in this tank as well as DI water.
50g BB tank with a 20g long sump and a RDSB
4 x 39w T5 HO lighting
a Koralia #3 & a Koralia #4
SpG = 1.025
Temp = 78F
0 ammonia, 0 nitrite, 10 ppm nitrate (don't have test kits for KH, Ca, or phosphate here at work today)

 

[peteyp923]

I dropped a small piece of LR on mine and the skirt shrunk in for a couple of days. now its doing fine and i grew from one polyp to three. i have mine on the bottom of my tank with 50k mh. i never fed them seems to be fine.

 

[Guygettnby]

i had a frag do the same thing when i was blasting it with light. were exactly is this frag placed in your tank? how much flow hitting it?

polyps can change for any number of reasons and sometimes without warnings.

 

[jeremyreef]

i would try moving them to less light

 

[fsn77]

The frag is slightly above the midline of the tank and receives what I would call a moderate amount of flow. I'll move them down a little lower and see if that helps their color.