Seriatopora (Birds Nest) Question

[NeverlosT]

Hello all,
I am the proud owner of a 150g SPS cube filled with happy acropora, millipora, pocillopora, and until recently seriatopora colonies. In the last couple of months my birds nests have begun to die, the polyps honestly look shaggy on them, and the tissue simply recedes from random spots. The green birdsnest was in the same place where it grew to a softball size colony from a frag. Same lights, same husbandry regime.

My ponape birds nest has suffered a similar fate, and now my rainbow birds nest is also falling victim. Now for the weird part, my other SPS are happy as could be. Millies growing like weeds, acropora colonies continuing to flourish. Montis good, zoas, LPS, even my big Magnifica nem all great.

My tank parameters have not changed much if at all:
Alk 9dkh
CA 450
Mg 1350
SG 1.025
pH fluctuates from 7.85-8.05 daily
Temp fluctuates from 77.5 to 79 daily
Phosphates are low. 0.03 ppm or less, right now they are 0.01ppm.
Nitrates not zero but low.
Lighting is an 8 bulb ATI T5 with all B+ and a couple coral plus and a fiji purple. Then two homemade RB LED strips front and back.

Basically, all seems to be well, except for the birdsnest, which I know, I know... is usually the first SPS most people keep....

Any ideas? Things are pretty far along now on all three colonies. I see no parasites or stinging or any other issue. I run carbon and a small amount of GFO, have a fuge and 15 fish. oh and one SOB sally lightfoot who eats anthias. grumble grumble...

thanks in advance.

Oh, to start things off, I was told a potassium deficiency could be an issue, so I plan to purchase a K+ test kit. Other ideas?

Heres the build thread if it helps: https://www.reef2reef.com/forums/club-cube/150802-neverlosts-140g-cube-paradise.html

 

[macscale]

IME Birdsnest is also the first coral to go wrong. They're funny like that.
The most common cause for receding on a BN colony in my experience an Alk swing. And they react quickly.

 

[declanisadog]

I was thinking ALK as well. If my ALK gets even a little high, my ponape BN gets burnt tips immediately.

 

[NeverlosT]

Thanks mac. I use a large CA reactor to maintain alk and calcium. Typically it is pretty rock solid but i will make a point of checking every few days, see if i can see a trend.

Question for you: what magnitude change in alk over a day or two would you consider an "alk swing"? 0.5 dkh? 1dkh? 1.5 dkh?

 

[macscale]

Anything as little as .5 of a dkh has affected my birdsnest. I lost a whole 5" colony froma 1dkh alk swing, it just depends on the specimen.

 

[NeverlosT]

hmm. I'll track the alk closer (currently only test once every 2 weeks), see what happens. It seems that with stable alk the corals should rebound, but the trend has been a steady decline. Good comments, any other ideas from the gang?

 

[macscale]

I mean the pottasium... but thats very unlikely.

 

[ajl]

I know this thread is really old, but I've just stumbled across a solution to a problem like this. I generally run with Nitrates less that 5ppm and phosphates close to 0. And my Seratiopora have never thrived. However, I recently was traveling for about a month and, while gone, i inadvertently doubled my pellet auto feeding. I ended up with pretty dirty water, though my refugium kept the nitrates close to 10ppm.

My Seratiopora did well while I was away.

When I returned, I fixed the feeding and skimmed more to get on top of things. To my surprise my Seratiopora started dying back. This was disappointing but, like I said, I am used to this.

Then, after getting nitrates and phosphates back down, I decided to do another round of Flucanazole to treat my bryopsis, which had come back. In order to do this, I needed to turn off the skimmer and the Flucanazole is also not great for my macro algae. So, my nitrates went back up to 10.

To my surprise, my Seratiopora started coming back! Has anyone else experienced Seratiopora doing better with semi low nutrients than low?