Favia purging?

I think my favia may be purging it's zooxanthellae but I'm not sure why. I purchased it about three weeks ago (a recent import) and it has looked fine during that time. The only thing I did notice is that I never could get it to feed. It would send out sweepers at night along the perimeter and there is no sign of tissue regression. The tank specs are as follows:

47 Gal Bowfront
Temp 80
Ammonia 0
Nitrite 0
Nitrate 0
pH 8.2
Phosphorous 0
dKH 9
Calcium 520

The lighting has changed a little. I originally had a three tube 36" standard (T-8) fluorescent fixture with two 10k and one actinic. The lighting set-up is only temporary. 7 days ago I added a 2-bulb 36" T5 HO actinic lamp as well. The fixtures set on the tank rim and this coral is about 6" below the water surface. I have a platygyra just a few inches away (out of sweeper reach) that seems to be fine. Here is a photo of it expelling some black mucus from the polyps. The photo is a bit overexposed but shows what was happeing. Any thoughts on why or what may happen next?

 

It is expelling waste most likely, although you have greatly increased your light output with the change. Lower both corals to the sand or lower portion of your rocks or they will lose much of their color IME.

 

Thanks for the response. If it is just waste I will feel much better. I did not think the lighting would be too strong. If anything I thought it was still pretty weak. You really think they could fade on just those bulbs?

 

Yes definitely the lights could cause problems without acclimating even with actinics. You probably have doubled the PAR output in your tank.