Is this STN?

[KMench]

I've attached a few pictures of two corals I'm afraid have STN. The pink one has been losing some tissue from the underside of the coral since it was eaten by a whelk. I fragged the white portion where the whelk had eaten the tissue, but the white still seems to be growing on the underside. The other coral has good color on the top, but yet again is stark white for a portion of the underside of the frag. Any suggestions?

 

[KMench]

I should also add that my tank is relatively new, and I have not yet had to dose anything. I checked my alk on Saturday and found it to be 6.5 I raised it back to around 8 by dosing baking soda. 1 teaspoon on saturday and 1 teaspoon today. Would 6.5 be a low enough alk level to lead to STN?

 

[erky]

nitrate and po4?

 

[KMench]

last time I checked, nitrate was 5 and PO4 was between 0 and .25. I'm sorry that first set of pictures is pretty terrible

 

[KMench]

Ok, I re-checked the parameters in question. Nitrates are about 5, phosphate registers 0 on the API kit. (Pretty sure this is inaccurate as I can grow algae like a champ lol). pH was 8, it's aways run a bit low. The pink abrolhosensis looked great up until that whelk had a snack, since then it's slowly progressed which is what's worrying me. None of my other corals have this problem with the exception of these two.

 

[29bonsaireef]

Seems to be more of die-off in the shaded areas. You could call it STN.. I guess? They don't look that bad on top where they're getting light, just the undersides. This will happen sometimes if lighting isn't well spread. The coral can still live and grow with this, but the tissue on the underside might not come back.

 

[NikoO]

That looks like stn to me. If you look closely can you see dead tissue on/around where the skeleton is exposed?

 

[KMench]

I wouldn’t really say I see any dead tissue, it kinda just goes from looking perfectly healthy to stark white. I’m ok with it being die off from shade, I just don’t want the whole frag to die off.

 

[Kremis]

that looks like STN to me. die off from shade happens VERY VERY slowly. since the rest is still bleach white that leads me to believe this happened quickly as no algae has grown there yet. What i usually do for STN is superglue around the dead part(leave like a milimeter of live tissue in between the glue and the death to be sure nothing spreads)

 

[KMench]

I would be inclined to believe the first frag is just shad then since that’s been about two months. The second one I’ll put some super glue on when I get home later. What’s the survival rate for stn?

 

[29bonsaireef]

I would be inclined to believe the first frag is just shad then since that’s been about two months. The second one I’ll put some super glue on when I get home later. What’s the survival rate for stn?

If you're parameters are good it can definitely be reversed. However, abros are not the easiest acro to keep, they need a ton of light, ime.

 

[KMench]

I have other acropora that are doing fine, so I guess I’ll hold out hope! On that note, hopefully catching the low alk and bringing it back up helps fix it.

 

[KMench]

Super glue has been applied ;Bookworm thanks for the tip. I’ll post updates one way or another.

Kyle

 

[Kremis]

whenever I see it I put superglue, better safe than sorry IMO

 

[KMench]

Yeah it’s already done lol. It’s about the same height as my maxima so it should be getting sufficient light.

 

[Som1else]

If it had been a larger frag i would re-frag it as far away from the affected area as possible

 

[rosshamsandwich]

LEDS?

 

[KMench]

Yes I have LED lights.

 

[Syoung]

I should also add that my tank is relatively new, and I have not yet had to dose anything. I checked my alk on Saturday and found it to be 6.5 I raised it back to around 8 by dosing baking soda. 1 teaspoon on saturday and 1 teaspoon today. Would 6.5 be a low enough alk level to lead to STN?

Anecdotally, I'd say 6.5 dKH could be low enough to STN. I had some major problems at 6 dKH, with the exact STN you are describing.

Are you planning on kalk or 2-part to maintain alk? Even with few SPS, coralline growth can rapidly deplete it.

 

[KMench]

I don’t believe I need to dose, but I need to monitor my dKH more often. I had been checking only about monthly because my tank is ~8 months old now. I had never seen a significant change in dKH from around 8. I had last checked it mid January and it was the same as always, 7.6. I did not check it again until last weekend and found it to be 6.5. Since then I’ve doser some baking soda and checked daily. I brought the dKH up to ~8 and haven’t seen a change since I brought it up. I’m thinking I’ll just check it once or twice a week, but since I haven’t seen any drop this week maybe I just need to dose occasionally? If I’ve corrected the dKH from 6.5, do you think the STN will stop?