Marks on SPS

[Crashjack]

I've got some marks on some SPS and don't know why or what is causing. I've attached pictures of bird nest, cyphastrea, plating montipora, and setosa. These come and go, and on the setosa, it seems to come/go in the same places. I see no "bugs" and am not sure that all of the marks are related (for instance, the lone bird nest mark might have occurred during maintenance). I'm not seeing anything on true acros, though I don't have any large colonies. I even wonder if it could be caused by blowing sand/detritus as during certain times of the day, I have my Gyres blowing hard enough to pick up and blow around fine sand particles/detritus. However, it isn't blowing so hard that my sand shifts around.

My tank is 72" x 24" x 19", and my lighting is a Nano Box Reef 5' LED/T5 hybrid fixture (a modified ATI 6-bulb T5 fixture that now has (4) 80w T5s and (8) LED pucks). My parameters have been running:

Alk: low 8's dkh, staying within a .5 dkh range testing 2x per week.
Ca: around 440 ppm
Mg; 1305 ppm*
pH: Maxes out around 8.38-8.42 daily as I have to run kalk 24/7 to almost maintain Alk/Ca (still lose about .15 dkh Alk/day, which I make-up dosing sodium bicarb. and CaCl every 3 days).
Nitrate: 10 ppm
Phosphate: .07 ppm
* Mg had been running near 1400 and then I got a 1305 reading. After dosing enough Kent Mg to raise 50+ppm, I got 1305 ppm again a week later. I've got a new test kit on the way.

This has been occurring for several weeks and like I said, spots appear and then grow back over. Any help would be greatly appreciated.

 

[bubbaque]

Have any blennies?

 

[jda]

Did something caustic fall on them? Salt creep, kalk paste, calcium chloride?

You can get some LED light burn if used too strongly, but I would think that it would be more widespread.

 

[Crashjack]

Have any blennies?

I have a Starry Blenny but for only 3 weeks. and this has been happening with the setosa for 2+ months. I also have a Harptail (fang) blenny that I've had for probably close to 1.5 years. Along with those two fish, Inhabitants that have been around long enough to cause are 2 fairy wrasses. Melanurus wrasse, kole tang, 2 Ocellaris clowns, longnose hawkfish, and a yellow watchman goby. Now, I have also had 3-4 emerald crabs and just added a few more, which was one of the possibilities I thought of, but they wouldn't explain the same location on the setosa.

Did something caustic fall on them? Salt creep, kalk paste, calcium chloride?

You can get some LED light burn if used too strongly, but I would think that it would be more widespread.

Licked aiptasia problem so haven't shot any aiptasia with kalk in a while. I run pretty good current most of the time and have never seen creep stay together long enough to land and sit on anything. It also wouldn't explain same location on setosa.

Regarding LEDs, I haven't adjusted intensity in quite some time (well before this started occurring).

Also, I was running Fluconzole for quite a while due to a bryopsis problem, which was what I thought might have caused the issue with the setosa, but that should be well out of the system.

 

[bubbaque]

I have a Starry Blenny but for only 3 weeks. and this has been happening with the setosa for 2+ months. I also have a Harptail (fang) blenny that I've had for probably close to 1.5 years. Along with those two fish, Inhabitants that have been around long enough to cause are 2 fairy wrasses. Melanurus wrasse, kole tang, 2 Ocellaris clowns, longnose hawkfish, and a yellow watchman goby. Now, I have also had 3-4 emerald crabs and just added a few more, which was one of the possibilities I thought of, but they wouldn't explain the same location on the setosa.



Licked aiptasia problem so haven't shot any aiptasia with kalk in a while. I run pretty good current most of the time and have never seen creep stay together long enough to land and sit on anything. It also wouldn't explain same location on setosa.

Regarding LEDs, I haven't adjusted intensity in quite some time (well before this started occurring).

Also, I was running Fluconzole for quite a while due to a bryopsis problem, which was what I thought might have caused the issue with the setosa, but that should be well out of the system.

It could possibly be the blenny. Google blenny eating sps and the bite marks look similar to what you’re experiencing.

 

[Crashjack]

It could possibly be the blenny. Google blenny eating sps and the bite marks look similar to what you’re experiencing.

The only thing is, I mostly see issues with bicolor blennies. Fang blennies are a different genus and are planktivores. Unlike most blennies, they have swim bladders and don't perch (they reside in the water column). I'm not saying it couldn't be the culprit. I'm just saying that my fang blenny is very different from what I saw as potential sps biters.