White fluff on certain acropora colonies, no bugs or bite marks. (video)

[Nburg's Reef]

So I noticed this white stuff on a few of my acropora colonies. it doesn't look like red bugs, as I had them a year and a half ago and eradicated them with several rounds of interceptor. I don't think its AEFW as they are not bare bite marks, its more of white fluffy stuff, almost like little bryozoans .



Note the spots flow and jiggle in the current. First 30 seconds is the worst of it, the weird thing is that coral is still growing quickly. I started noticing the white stuff last weekend, thinking it was just sand/debris bits as the wrasse has been dropping sand everywhere. @ 50s shots of the other colony that has issues, STN under and 1 of the top branches looks like its on its way out.

Little background: in early November, I made a mistake and left my dosers on for several hours and my alk shot up to 16dkh. I let it drop naturally over a few days and its been rock solid at its normal 7.6 kH since. My nutrients just dropped to .25 ppm NO3 from around 3-5 ppm so the corals may be starved a bit, but its been a short term drop (not out of the ordinary for me as I have to dose KNO3 every now and then). Other thing was a week ago, I stopped spot treating LR areas with hydrogen peroxide to kill some pest algae, not full tank dosages. other than that, Not sure what else could cause it.

Another coral had a STN spot that stopped, but there are other sections of that coral that look like there is some local rotting or STN. doesn't look dead, but it looks like it might be on its way out.

I have not noticed any dead circles/spots notoriously found in AEFW and I haven't seen eggs.

 

[DSC reef]

Could possibly be anthropods. @Tahoe61 any idea? I don't see any damage to the coral.

 

[Nburg's Reef]

Yeah, no damage that I can see and the coral doens't seem stressed. i thought it was stuck on debris, but it doesn't come off with a turkey baster.

The coral @ 50sec does have damage, but no white stuff. That one might be from the alk issue.

FWIW, I turned all the pumps off so the water was still and didn't see any movement from the white areas. Typically when the flow is shut off, red bugs will dance around a bit.

 

[29bonsaireef]

Might be mesenterial filaments. I have corals that do this from time to time, usually after fragging something, touching corals, or if there's an injured coral in the tank. Definitely a stress signal, I've noticed quick change in temp/salinity will also bring these out. Not a huge deal, they usually go away after a day or two.

 

[Nburg's Reef]

I was thinking that too. There has been some stress in the tank over the past 2 months. I'm trying to stabilize things now. Otherwise that coral looks good on top and has shown great growth thru the period of stress. And another coral is not doing well, so maybe that's it.

Just glad it doesnt lool like AEFW. If that was the case i would give up on Acros until i get a large system. Acros in a 40g is challenging.