Sudden bleaching of a stylopora

[RyanTheSquid]

I have had this stylopora for around a year, not much growth but it has grown at least. Out of nowhere, with no change in the last 2 weeks or so, this white bleached strip appeared overnight. I added 2 acros from SBB corals just about 2 weeks ago, one was a smooth skinned acro, I think thats what they are called at least, it never colored up and began bleaching from the bad, now fully bleached. The other acro seems to be doing well, has some red and green, looks great. My calcium is at 415 and alk at 11.3, up from 9.3 roughly a week ago, but I have dosed nothing but AFR since then. I am not sure why alk would be raising so much, could this cause the sudden bleaching? My system has been consistently around 9 to 9.6. I was dosing magnesium and carbonate 2 times a week each till it was reccomended it just dose AFR.

 

[Tahoe61]

That's a normal growth pattern on the tips.

There is STN at the base though. I would stop or dramatically reduce the AFR dosing, or double check the test until the vslues dirfts down to NSW values.

 

[RyanTheSquid]

That's a normal growth pattern on the tips.

There is STN at the base though. I would stop or dramatically reduce the AFR dosing, or double check the test until the vslues dirfts down to NSW values.

Is STN reversable or just able to be stopped at least? Should I do a large water change?

 

[Reefer Matt]

Yes, unstable alkalinity can cause sps coral to stn. (Slow Tissue Necrosis). A 2 dkh swing is too much usually. If you overdose AFR, it will take a few days to show up, it needs time for bacteria to process it. So you might have overdosed and not known it until now.

 

[Tahoe61]

Is STN reversable or just able to be stopped at least? Should I do a large water change?

Stylophora are hardy sps. Backing off on the dosing might do the trick, but if it doesn't consider fragging above the the white skeleton line.

 

[mcarroll]

Everything looks a little too clean and the crab in two of the photos looks HUNGRY.

Are these corals also a little hungry? I see no mention so far, how are dissolved nutrient levels? (no3,po4)

I would keep that crab well fed, not as CUC.

 

[Krux]

You may want to do a series of water changes to slowly bring alk back down instead of waiting for it to drop.

 

[mcarroll]

Sorry for posting twice, but I literally forgot the second part of my post...

Nutrients would be my main question....it looks like the coral is phosphate starved and losing control over symbiosis as a result causing the STN and bleaching.

For coral recovery I would hope to see the tank's PO4 level at ≥0.10 ppm and NO3 at ≥ 5 ppm.

It's hard to tell in the photos, but do you think your euphiliias look light colored or faded at all?