RTN at base of Bonsai

[alten78]

Hello all, unfortunately I'm having a bit of an issue with my Garf Bonsai and RTN at the base. Things overall have been progressing very nicely for awhile and growing quite a bit so seeing this today took me back some.





Preliminary tests are -

SG 1.025
Temp 77.2-80
PH (Apex) 8.34
Alk (Hanna) 7.38
Ca (API) 520
Mg 1500 (nyos)

Two weeks ago I switched from 250w MH/T5 combo to all T5's. I only top off fully saturated kalk but I noticed that without the MH's, Im not getting as much evaporation so alk that usually is solid around 7.5-8 has been dropping to 6.5-6.8 which i will dose about 2.5 ml of Bionic to bring it up (alk only). I was surprised to see the mg and ca that high today but didn't think it would cause RTN?

At what point do I need to frag this piece? Definitely dont want to lose it, grew it from a nub!

 

[w3bbo]

My money is on the drop in Alk or the fluctuation. It should recover in time and heal but keep a close eye on it as it may get a secondary bacterial infection. Mg is not normally an issue as long as it is raised slowly. Calcium is very high though.

 

[alten78]

My thought on the high calcium is that Im topping off with fully saturated kalk (which is struggling to maintain alk) but is more than my calcium need since both are dosed in equal parts with the kalk?

So far the tissue got a little worse at the base but has held steady over the night, will be testing again shortly and is my normal day for a water change anyways. I'll keep my eye on it for sure.

 

[jjoos99]

My guess is also alk like w3bbo mentioned. Also have you calibrated your refractometer to ensure of the proper salinity. I had the same issues awhile back and I had put too much faith in my meter, when I calibrated I was off by almost .05 points.
Jeff

 

[Myka]

I'd double check that Ca level with a better quality kit like Salifert or Elos. What are NO3 and PO4 at? The coral in question is close to the side glass, could you take a closer picture from that side?

Btw, that is STN (slow tissue necropsis), not RTN (rapid tissue necropsis, so you may find more help by searching for causes of STN. RTN is when you wake up and half the coral is gone or all of it.

 

[alten78]

I'd double check that Ca level with a better quality kit like Salifert or Elos. What are NO3 and PO4 at? The coral in question is close to the side glass, could you take a closer picture from that side?

Btw, that is STN (slow tissue necropsis), not RTN (rapid tissue necropsis, so you may find more help by searching for causes of STN. RTN is when you wake up and half the coral is gone or all of it.

After I made the post I realized my mistake of RTN instead of STN

Right now, most if not all of the base is bleached. I was going to wait until it started up the main stalk if you will before I fragged it but so far it seems like the damage is done and hasn't gotten any worse in the past week or so.

NO3 was at 10ppm (salifert)
PO4 was at .02 (hanna)

Both taken last week, was feeding heavier to bring both up some.

Since I moved away from MH's to all T5's, Im not evaporating as much water as I used to even with a fan blowing so less kalk is getting topped off which kept things solid. I have a bubble magus that I was going to setup when I moved everything to a newer setup but that's a few weeks/month away.