Acropora tissue damage? Not sure what this is

LivinTheSwreefLife · Jul 1, 2017

I have had this acro for about 2 months. It recently started showing very tiny patches of what looks like tissue damage (but could be algae growth I guess? I am not sure). It is getting worse now, and is mostly on one side (side opposite the powerhead where flow is lower). Here is a pic, I am referring to the whitish/clear spots on the left:

Is this tissue damage, possibly from my arrow crab? Is it expelling zooxanthellae? I was able to get some to blow off with a turkey baster but not all, here's what it looks like after blasting with baster:

Flippers4pups · Jul 1, 2017

Do you dip your corals? Flatworms? Acro bugs? Can you dip the coral in question to see if something comes off?

LivinTheSwreefLife · Jul 1, 2017

I dip with Melafix when I add new corals. This coral is heavily encrusted on a very large rock now, in order to dip again I would have to break it off which I would rather not do unless it was a last resort situation.

Fwiw, I have had flatworms in a previous tank and these don't look like flatworms on visual inspection. They "blow" with the tank flow, like algae would, or dead flesh. They look like either the coral's flesh is coming off, something is being expelled from it, or the very beginnings of algae growth, but I am not an expert.

LivinTheSwreefLife · Jul 1, 2017

Tank parameters:
Temp: 79.8 degrees
SG: 1.023
Alk: 8.9 dkh
Calcium: 460 ppm
Nitrate/phosphate: 0 (both used to register low amounts until I got some cyano which seems to be using it up)
Ph: 7.8

I have been turning up my LED lights 1%/day, if that matters.