Thoughts on this damage?

Nutter · Feb 19, 2018

Good morning Reefers,

I noticed this large damaged area on one of my acropora last night. Nothing has been added to this tank in months, and this coral had no damage at all just a few days ago. I don’t know how it could be AEFW, but I wanted some input from people with more experience than me:

Any thoughts?

happyhourhero · Feb 19, 2018

Is it possible to get a better pic of the damage area...maybe with a flashlight or at least very little blue?

SEMA · Feb 19, 2018

There's a possibility it could be AEFW, but from the photo, it doesn't look like it. A colony infested will usually have little circles of eaten flesh on all undersides, and take a while IME for them to eat a huge patch like you have.

This looks like a STN. Any corals local to the colony that could release sweeper tentacles at night? Any crabs calling the colony home at night? How long between water changes? Any temp dip/spike? Sudden PH drop? Alk spike/drop?

STN usually IME comes from a sudden change in chemistry or corals fighting/getting to close. A drop in nutrients could also trigger this if lighting is strong with a slightly higher DKH then NSW. First thing I would do if the cause is unknown,increase flow, test all parameters, 25% h20 change now, 25% change in 5 days, test parameters and correct. Go over any dosing equipment to make sure it's working flawless with no line cloggs. If it's been 6 months without cleaning power heads and pumps, clean them to restor optimal water movement. Look for any stagnant areas with detritus accumulation and vac out.

To find pests, look at night after lights been off for awhile. You will have to look very closely as many pests are 1mm or less in size and hide very well.

Nutter · Feb 19, 2018

Will get a better picture today, absolutely.

There have been no changes in any measured levels. 8.1 dkh, 420 cal, 5 ppm nitrates, .07 phosphates. Perhaps the Jack-O-Lantern below it reached up and stung it? I didn’t think it was close enough, but I suppose it is possible...either way, glad to hear that it doesn’t look like AEFW.