Staghorn coral concern...

[DAvis]

Hey all,
I bought this staghorn frag at our local frag sale in Syracuse (abcreefs.com, Yay! shameless plug!). Here's a picture back in December, about 1 month after purchase.
Looks great!

 

[DAvis]

Here it is 4 months later.... It has grown nicely and the polyps are fully extended. Then I noticed the bleached basal stalk, devoid of any polyps! What is happening? I handled it once to recement about 2 months ago. Did I do this much damage, or is something else going on. I don't see any sort of causal agent... I haven't taken any action yet, though I was thinking a Lugols bath in case of some sort of infection/pathogen.

 

[DAvis]

Forgot to mention...
Tank parameters are fairly normal:
pH 8.2
NO4 < 5.0
PO4 < 0.25
Ca 480
Mg 1400

BUT.... my alkalinity was low, around 6 dKH, and I raised to 9 dKH with baking soda over the course of a week. Any thoughts on this? A little worried, it's a beautiful little piece!

 

[valasaraptor]

most likely the coral is making a shadow and isnt getting enough light to the base

 

[little_fish]

No, that isnt the case

My concern is that it is slow tissue necrosis. I would frag off the healthy part and toss what is dead/dying. Also that isnt a staghorn coral, it looks more like a birds nest to me

 

[DAvis]

My concern is that it is slow tissue necrosis. I would frag off the healthy part and toss what is dead/dying. Also that isnt a staghorn coral, it looks more like a birds nest to me

You are right, little, it's a Seriatopora caliendrum. For the time being, I did an Iodine dip (Coral Medic, Brightwell, Aq). I will monitor closely and frag if (when) necessary. It hasn't changed in 4 days, and I honestly don't know when it started. I only saw it 4 days ago.

Will keep you posted. Thanks for your help!