Why is my Acan loosing tissue??

[Paul87]

I've had this particular acan about 2-3 years and have never had a problem with it. I did however just move my 38 gallon tank and all inhabitants into this new 40 breeder tank I have setup now. Everything else is doing very well. I first noticed this spot on my acan a few days ago and it appears to be getting bigger each day. I was thinking maybe it was brown jelly disease because I did see a little bit of brownish tissue where the coral tissue is missing. It may be hard to tell in the photo, but its the best I could really get of it without unmounting it from the rock it is on. I know if it is brown jelly I will need to cut the healthy coral away from the bad spot. But could it maybe be something else? I really don't want to loose this acan! Thanks for any help in advance.

Link to larger photo:
Imgur

 

[mrcoffee2]

Could it be too much light?

 

[saltyphish]

I know mine started doing the same and had noticed my hammer coral had let loose a tentacle that landed on one of my acan polyps. Now I have the same problem, mine got a nasty sting I reckon.

 

[Paul87]

Both could be a possibility. The 40 breeder is shallower than my old 38. I cut it loose from the rock today and gave it a good dip. I mounted it lower than it was as well.