Is This STN?

[Shep]

Just saw this at the base of my coral. What's happening to it?

 

[cginter]

Could be few different things... How new is the coral? Did you acclimate the coral into your system? What's your Params at? Cal, alk, mg. phosphate?

Your tank looks fairly new from the pic, SPS require a healthy system that's been running for a while to have success, along with low phosphate.

 

[rockskimmerflow]

Check alkalinity first, phosphate next. Base up recession is usually linked to issues with those parameters or a parasite infestation in my experience. Looking at the picture I doubt it's a parasite so I would lean toward chemical or nutrient issues being the cause. Posting your basic water parameters will help us greatly in identifying the culprit.

The branch rock in the photo appears devoid of any coralline or green algaes - which makes me wonder is it a new tank?

Luckily the recession seen in the picture is very much reversible and once conditions improve the coral will re-encrust back down the dead portion of the base. Good luck!

 

[Shep]

I'll test those today but the tank is an upgrade from my 20g, used mostly old rock but added a bit of new rock.