RTN chain event, losing acro after acro

MrStoffel

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Hi All,

I don't post on reef2reef all that often since i am also active on a country specific forum, but i do read a lot on reef2reef.
I am a long time SPS keeper (20 years now), but am currently facing something i have never seen before.

First some background information about the system:
The system is 300L in total, running for 7 months now.
It was seeded with clean dry rock + cured live rock.
Salt used is tropic marin pro reef & parameters are kept stable with ati essentials pro & ati nutrition, controlled by GHL doser.
As for lighting i am using an ati hybrid with 4x39w T5 + 2 led clusters. STD ati settings.
ATO and temp are managed by a controller so very stable as well.
The sump holds a skimmer and refugium with chaeto lit by a kessil H80.
There is also some maxspect nanotech filtration media.
Flow in the tank is a maxpect gyre xf230 and two jebao 10000L/h SLW20's. All together they produce 28000L/h flow, so close to 100 times tank turnover.
However, the jebao's are running on pulse mode, so it will be closer to 50x.


I added coral at about the one month mark, as all measurements checked out.
From the start everything took off great, acros started encrusting very well, zoas and goniopora were looking super healthy, i was a happy reefer.
Suddenly a had a green tenuis rtn overnight. It looked great the evening before, and by morning 30% of the colony lost its flesh starting at the base.
The strange thing was that the living part still had nice PE and looked fine. I decided to give it a day => WRONG
By the next morning 80% was gone and i fragged what was left. I lost those bits over the next 2-3 days.

By that time i still thought this was a one off case of bad luck.
However a week or so after this event a nice frag of a suharsonoi started the same pattern. It had encrusted to the size of a golf ball. Lost that in 2 nights as well.
All other acro's looked fine, same for the other corals. As an example, my hawkins echinata has tripled in size in about 4 months.

By that time i started to measure daily and noticed my alk had crept up from my usual 8 to 8.9
A fellow reefer suggested this was probably the cause. So i lowered it again to 7.8 over the course of 2 weeks.
My nitrates were not very detectable with my testkits, but i feed 3-4 times daily so they were certainly not zero, they were just consumed very fast.
PO4 is always between 0,02 and 0,04 depending on the time of day measured.

A week after losing the suharsonoi a spathulata frag RTN'ed overnight.
I started looking in the tank at night looking for pests and found out i have a number of digitate hydroids.
Maybe these are the cause? However there are other acro's close to the hydroids that seem just fine.
Most were also deep in the cryptic areas of the rockwork.

Two weeks passed without losses, until last weekend a nice deep blue tenuis started RTNing.
This was a frag of about 8cm i got from a fellow reefer who had it for years. It was a very resilient coral that was looking incredibly healthy before.
Yet the same pattern repeated itself: day one 20% rtn at base, day two 50-80% gone, day three, complete RTN.

I am at a complete loss as to what to do. My parameters have been stable for weeks, my ATI ICP is at 98% without any parameter out of bounds.
At this moment i feel like i will loose the complete acro population over the next two months.

This week i will receive a UV steriliser and triton's RTN-x, those are my last hopes of stopping this.
I would appreciate any other insights or suggestions on how to overcome this.
 
Zoanthids

reefpizza

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Same situation here, icp perfect and super stable parameters, got some stn/rtn random, i have started dosing stn-x from Triton and i have done a 5 day treatment with Cipro, i think it's a bacterial issue.
 
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MrStoffel

MrStoffel

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Same situation here, icp perfect and super stable parameters, got some stn/rtn random, i have started dosing stn-x from Triton and i have done a 5 day treatment with Cipro, i think it's a bacterial issue.
I am indeed starting to believe it has to be some sort of pathogen moving from one host to the next.
That is why i hope UV sterilisation will help in reducing their numbers in the water column.

How is the stn-x working out for you?
 
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MrStoffel

MrStoffel

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Day1
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flyfisherman

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I think your tank isnt ready. I dont like this is only a 7 month old system. Even though you are seeding with live rock, how can everything including bacteria levels, ect. Be stable at 7mos to support acros.

It seems you are trying to fast forward the process of establishing a new tank. Start with digis, birdsnest add acropora later. Who knows maybe 1 dying acro in an unestablished system can cause the others to go down....i think you're paying the price for rushing delicate sps into the system for whatever reason.

I would keep adding cheap sps until this passes and or continue to check for metals and test parameters all the time since its a new system. Check for pests with lights off and uv light. Maybe nuke tank with dr. Gs but you are so unestablished not sure what the outcome will be....
 

reefpizza

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I am indeed starting to believe it has to be some sort of pathogen moving from one host to the next.
That is why i hope UV sterilisation will help in reducing their numbers in the water column.

How is the stn-x working out for you?
I'm 6 days in, something seem do, but i can't guarantee having done cipro right before, for now all the rtn stopped, and the stn seem stable, kh consumption is really low, hope to see improvements in 3/4 days also i turn down a bit the power of the light fixture.
 
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MrStoffel

MrStoffel

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I think your tank isnt ready. I dont like this is only a 7 month old system. Even though you are seeding with live rock, how can everything including bacteria levels, ect. Be stable at 7mos to support acros.

It seems you are trying to fast forward the process of establishing a new tank. Start with digis, birdsnest add acropora later. Who knows maybe 1 dying acro in an unestablished system can cause the others to go down....i think you're paying the price for rushing delicate sps into the system for whatever reason.

I would keep adding cheap sps until this passes and or continue to check for metals and test parameters all the time since its a new system. Check for pests with lights off and uv light. Maybe nuke tank with dr. Gs but you are so unestablished not sure what the outcome will be....
Yes maybe you are right. However i think i need to clarify how i build up this system.

June 2020: Purchase 10kg live rock, start curing in a bin in my garage with heater, powerhead and some small light to look for possible unwanted hitchhikers.

August 2020: acid wash 30kg of dry used rock, very porous top quality rock
This rock was added to the live rock + seeded with some extra bateria and ghost feedings

October 2020: Tank filled with cycled rock + live sand caribsea + 1L of sand from an established reef tank's DSB
November 2020: first fishes
December 2020: first corals
Januari 2020: first acros (by this time the bacterial population in the rocks was 6-7 months old)

I also use aquaforest Life source every month.

While the tank may be young, i believe the bacterial population is certainly developped good enough to support acropora. (if you are referring to the nitrification cycle)
I do think it is possible that some type's of bacteria needed to protect the coral from unwanted viral or bacterial infections are not developed enough.

For sure i will not be adding any acro's until this is resolved.
 
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MrStoffel

MrStoffel

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I'm 6 days in, something seem do, but i can't guarantee having done cipro right before, for now all the rtn stopped, and the stn seem stable, kh consumption is really low, hope to see improvements in 3/4 days also i turn down a bit the power of the light fixture.
My kH consumption has not really been affected by this. It remains very stable and at a normal level for the number of corals i have. I believe this to be due to RTN affecting only one coral at a time.
 

guylaga

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Thinking outside the box here.

Try fragging off a few pieces of your currently healthy looking acros. Put them on frag plugs but don't epoxy to the rock work.

If these frags start to RTN try dipping in Prime or Coral Rx ect... and see if this can slow or stop the tissue loss.

Might give you some clues on how to combat the issue.
 
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MrStoffel

MrStoffel

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Could it be that the digitate hydroids are irritating the base of certain acro’s causing them to become weaker or get a small exposed spot after which a bacterial pathogen is able to enter the coral skeleton and cause the RTN?
Today i added a UV steriliser in hopes of destroying the larval stage of the hydroids, maybe also reduce their foodsource a bit and who knows maybe it can also lessen predatory coral pathogens. Other than that i wouldn’t know what else to do, maybe the best course of action would be to do nothing?
Values of todays measurements:
Kh: 7,7
Ca: 440
No3: 3
Po4: 0,03
 
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MrStoffel

MrStoffel

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Have you dipped for flatworms at all? That first picture almost looks like it has a few bit marks or flatworms just above and to the left of the RTN section.
Yes offcourse, i dip every coral with 2 different dips before it goes in the tank. Even then i watch them with a magnifying glass while on the frag rack for the next two weeks. I am 99% certain its not aefw, also because i am very carefull where i buy my corals. Here is a pic of the coral when it was still healthy. The skin just looks like this.
C26FC535-88B4-4624-8D72-33017614819F.jpeg
 

sculpin01

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Did you purchase some maricultured frags? They are known to harbor diseases.

Looks to me like bacterial RTN, (possibly a Vibrio sp. ?). I would try an amoxicillin dip of the affected frags.

If you want to read about how a similar situation was halted with the critically endangered/nearly extinct remaining Florida Dendrogyra cylindricus colonies, take a look at this link:

 
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MrStoffel

MrStoffel

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There is one frag that potentially came from a chopped up mariculture piece. Its also the coral that didn’t die overnight compared to the others. It has bald spots all over but keeps hanging in.
 
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MrStoffel

MrStoffel

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An update:
Yesterday i installed a uv, it can’t hurt and who knows maybe it can help kill off a waterborne parasite.
Today i received triton rtn-x and made a small container with the recommended “intense” dose. Put all affected pieces in there and left for 15 minutes.
Heres some pics and a video of what i found...
11945AFB-8E02-4DEE-A556-9F6150ACCB20.jpeg
3C0E850E-D9EE-48F0-8477-358D13DBEE59.jpeg
1D4A17DF-464A-4AF5-96FA-339047186D0F.jpeg
DEA07695-2242-48B7-A057-4B81E2C48E9E.jpeg
8653C1F6-99AD-456B-88D1-7055DD33AE94.jpeg
976C78AD-5995-43D0-B586-16467A008528.jpeg
3E166B99-FF13-46AC-AEA1-3FEFA6FC1979.jpeg
 

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