Birdsnest - Base bleaching white

[dhof]

Approaching my 2 year mark on a mixed SPS/LPS tank. All the SPS are doing fantastic, and I've had a few LPS issues in the past 2 years from what I believe now was too intense lighting. 2 weeks ago, I did adjust my lighting intensity down about 25% lower. In the past 5 days, my large birdsnest colony, (which grows so fast I have to trim it every month or two), started bleaching from the base up. The bleaching appears to be getting worse every day. I believe the remedy is to frag a healthy arm and start over, but i really would rather not do that. I wonder: do you think that the bottom part is bleaching just because the top is so full and no longer getting enough light? Using a magnifying glass, I do not see any sort of bugs or anything. I have not had any recent additions or changes to the tank, but 2 weeks ago I lost a trachy from perfectly healthy to completely bleached in 48 hrs out of nowhere (I think that lighting was too intense)

parameters are stable: Alk 10.5dkh, Cal 420, Mg 1440, Nitrate 4, Phos 0.03, Salinity 34.4, ph 8.0-8.3, tmp 78.8

Here's a pic:

 

[anthonys51]

Why did you decrease your lighting

A trachy who has been in your tank for months wouldn’t just all of a sudden bleach from lighting.

While the birdnest is growing I do notice the base is dead and growing coraline algae on it. Could be too little flow or not enough like or both
Flow is very important for bigger colony’s like that to remain healthy

 

[LobsterOfJustice]

I have experienced this several times and always blame it on lack of flow and light due to their tight growth pattern. But interested to hear what others have to say.

 

[Waters]

I don't think that is bleaching.....that looks like STN/RTN which is a whole different issue. Birdsnest corals are normally one of the first coral to watch for something not being right......whether it is flow, lighting, water quality, etc. Reducing your light by 25% is a lot to do at one time.

 

[LobsterOfJustice]

I don't think that is bleaching.....that looks like STN/RTN which is a whole different issue.

That is correct. Sometimes people inaccurately use the terms interchangeably, but that coral is not “bleaching”.

 

[little_sardines]

I would agree it looks like a flow problem. When colonies get big like that it's tough to get flow down into the middle and they can RTN from the center out.
You could probably trim the colony into smaller chunks and reglue them to the rock? I know it sucks to cut up a big colony you've grown but it happens, unfortunately.

 

[anthonys51]

Yes I would agree I would cut colony up too.

Also I would invest in an ice cap gyro. Think they are like 125 bucks and they really move a lot Of water around. I like mp40 but way more expensive. But mine are 5 years old

Those are the 2 choices I would get for flow imo

 

[dhof]

Thanks guys, that's just what I needed. I'll be attacking flow tonight! Probably going to have to trim it into smaller chunks, but I'll wait a week to see how things progress first.

 

[dhof]

So as an update, I adjusted the flow, but the birdsnest continued to deteriorate. By Friday it was 80% melted from the base, and moving quickly. I fragged 11 viable arms (fragged above the healthy tissue line) and 3 of the Frags melted on Saturday, 2 melted on Sunday, and another 2 melted today. Of the 4 that remain, 2 look totally healthy and the other 2 are questionable. I'm hoping at least 1 survives so I can regrow it, as the colony was spectacular before this happened.

I have another colony of Blasto, which is really a show piece of my tank (one of the biggest and thriving coral colonies in there). About the same time as the birdsnest debacle, the blasto started looking 'sad' and not as full as normal. By Friday, all the polyps were seriously retracted, but no signs of tissue loss, just retracted. I gave the blasto an iodine dip yesterday evening, and he still looks pretty sad.

Then today, I have this beautiful Acro colony about the size of a softball, which one of the lowest arms has turned white. I believe this turned white since just yesterday as I would have noticed this before. So I'll keep a close eye on this one...

I'm at a loss as to what could be causing this. Today's readings are Alk=10.65, Cal=396, Mg=1411, ph=8.0to8.2, tmp=78.6, salinity=34, ORP=271, Nitrate=8, phosphate=0.05, Iodine=0.06, Potassium=lower than 320 (the potassium test never turned color on the Red Sea after 0.5ml of titrant).

The postassium is worrisome at 320 or lower. I want to repeat the test before I take action, but I'll have to repeat the test tomorrow since it is so time consuming. I did a 15% water change on Saturday and another 15% water change on Sunday, so I'd be surprised if the potassium is actually that low.

I'm baffled, and could use any hints of things to check or tecniques to try. Reading online, it sounds like sometimes this RTN just takes hold and there isn't much to do. Any brainstorming is appreciated.