STN - stumped

[tymo92]

Been dealing with stony coral issues for a couple months now and can’t figure out why. Very slow tissue recession, not affecting all species but has killed a few SPS frags and is causing issues with some favias as well. On acros it shows up first as mesenterial filaments and sliming tips, then recession from the tips and edges at the base.

240 gallon system, 7 months old.

Parameters:
Alk 7.5
Ca 430
Mg 1375
NO3 5ppm
PO4 0.02ppm
PH 8.3-8.5
Temp 76
Salinity 34ppt

Low nutrients has been my operating assumption for what is causing it but I feed heavy and have 23 fish, and there is plenty of film algae growth on the glass. Many reefers keep nutrients at these levels and haven’t had these issues.

My next best guess is something bacterial, perhaps brought on by stress from low or bottoming nutrients.

2 ICPs did not flag anything particularly abnormal other than low/zero phosphates, and 0.018 ppm of copper in a recent test (should not be too high to be causing these issues).

Acros are in 200-250 par for the most part. I’ve also lost a birdsnest and stylo and I would describe the losses there as flesh peeling from the skeleton.

Would be great to figure out what is going on here.

Pics of some of the affected corals attached.

 

[Marine Betta]

Been dealing with stony coral issues for a couple months now and can’t figure out why. Very slow tissue recession, not affecting all species but has killed a few SPS frags and is causing issues with some favias as well. On acros it shows up first as mesenterial filaments and sliming tips, then recession from the tips and edges at the base.

240 gallon system, 7 months old.

Parameters:
Alk 7.5
Ca 430
Mg 1375
NO3 5ppm
PO4 0.02ppm
PH 8.3-8.5
Temp 76
Salinity 34ppt

Low nutrients has been my operating assumption for what is causing it but I feed heavy and have 23 fish, and there is plenty of film algae growth on the glass. Many reefers keep nutrients at these levels and haven’t had these issues.

My next best guess is something bacterial, perhaps brought on by stress from low or bottoming nutrients.

2 ICPs did not flag anything particularly abnormal other than low/zero phosphates, and 0.018 ppm of copper in a recent test (should not be too high to be causing these issues).

Acros are in 200-250 par for the most part. I’ve also lost a birdsnest and stylo and I would describe the losses there as flesh peeling from the skeleton.

Would be great to figure out what is going on here.

Pics of some of the affected corals attached.

I’m sorry you’re dealing with this. The salinity could be a tick higher, but that shouldn’t be causing these issues. I would say your low nutrients are a big part of the problem. I normally shoot for 10-20 ppm nitrates and 0.04-0.08 ppm phosphates, but I know people who have awesome sps tanks with higher nutrient levels.

This would need to be confirmed by someone like @Randy Holmes-Farley, but I believe that the copper may be part of the problem as well. It’s low enough to not cause immediate issues (RTN), but if STN has been a problem for a while, I would say the elevated level of copper has something to do with it. I’m not sure which ICP company you used, but Fauna Marin recommends copper concentration between 0.002 and 0.006 ppm (2-6 micrograms/Liter).

Did your ICP test include a sample of your RO water? It could potentially be contaminated. That’s the only other factor that I can think of being the cause of the problem.

 

[tymo92]

I’m sorry you’re dealing with this. The salinity could be a tick higher, but that shouldn’t be causing these issues. I would say your low nutrients are a big part of the problem. I normally shoot for 10-20 ppm nitrates and 0.04-0.08 ppm phosphates, but I know people who have awesome sps tanks with higher nutrient levels.

This would need to be confirmed by someone like @Randy Holmes-Farley, but I believe that the copper may be part of the problem as well. It’s low enough to not cause immediate issues (RTN), but if STN has been a problem for a while, I would say the elevated level of copper has something to do with it. I’m not sure which ICP company you used, but Fauna Marin recommends copper concentration between 0.002 and 0.006 ppm (2-6 micrograms/Liter).

Did your ICP test include a sample of your RO water? It could potentially be contaminated. That’s the only other factor that I can think of being the cause of the problem.

Thanks for the comments.

I am definitely trying to bring up nutrients. I just struggle to find this as the sole reason given how just a few years ago so many of us were focused on striving for 0 PO4 and low nitrates and didn’t have these problems. But low nutrients, or bacterial infection, seem to be the most commonly cited causes for these unexplained issues when other parameters seem to be fine.

The copper showed up on a Reef Labs ICP from 2 weeks ago. I did some research and recall Randy commenting that he had somewhat elevated copper in a similar range and didn’t observe issues, but I can’t rule it out. I had an ATI ICP from December that found copper undetectable.

The recent Reef Labs ICP did not include RO sample, though the ATI one from December did and didn’t find issues. I run 2 carbon blocks, and 2 DI canisters and recently replaced the resin in 1 of them. Probably will replace the resin on the other just for peace of mind but I doubt anything is getting through.

 

[Marine Betta]

I’m sorry you’re dealing with this. The salinity could be a tick higher, but that shouldn’t be causing these issues. I would say your low nutrients are a big part of the problem. I normally shoot for 10-20 ppm nitrates and 0.04-0.08 ppm phosphates, but I know people who have awesome sps tanks with higher nutrient levels.

This would need to be confirmed by someone like @Randy Holmes-Farley, but I believe that the copper may be part of the problem as well. It’s low enough to not cause immediate issues (RTN), but if STN has been a problem for a while, I would say the elevated level of copper has something to do with it. I’m not sure which ICP company you used, but Fauna Marin recommends copper concentration between 0.002 and 0.006 ppm (2-6 micrograms/Liter).

Did your ICP test include a sample of your RO water? It could potentially be contaminated. That’s the only other factor that I can think of being the cause of the problem.

Thanks for the comments.

I am definitely trying to bring up nutrients. I just struggle to find this as the sole reason given how just a few years ago so many of us were focused on striving for 0 PO4 and low nitrates and didn’t have these problems. But low nutrients, or bacterial infection, seem to be the most commonly cited causes for these unexplained issues when other parameters seem to be fine.

The copper showed up on a Reef Labs ICP from 2 weeks ago. I did some research and recall Randy commenting that he had somewhat elevated copper in a similar range and didn’t observe issues, but I can’t rule it out. I had an ATI ICP from December that found copper undetectable.

The recent Reef Labs ICP did not include RO sample, though the ATI one from December did and didn’t find issues. I run 2 carbon blocks, and 2 DI canisters and recently replaced the resin in 1 of them. Probably will replace the resin on the other just for peace of mind but I doubt anything is getting through.

The acros STN’ing from the tips does sound like alk burn/burnt tips. This is normally caused by low nutrients and high alk (+9 dKH). In my experience, an alk of 7.5 dKH wouldn’t cause this, but it’s possible. Was your alk higher than this at some point? Sorry if I missed this, but do you dose nitrogen and phosphates? Do you dose amino acids or any other coral food?

If it’s bacterial, you can try an iodine dip. If that doesn’t work, you will likely need to treat with antibiotics in a separate tank.

Let’s see what Randy or someone else says about the copper. I think 0.018 ppm might be pushing it. From what I remember, Randy’s copper was somewhere between 0.01-0.015 ppm. I’ve always been told 0.02 ppm and above causes issues. Are you dosing copper or using a product that contains copper? Any metal fittings or metal stand? I don’t think it would hurt to run cuprisorb to be safe.

Ok, it’s probably not the RO water then.

 

[JonoH]

7 Months in...my uneducated opinion is that its perhaps too early for SPS. I struggled to keep them till i basically hit the 12 months point.

I know others say and have great tanks that do otherwise...just my experience

 

[Som1else]

You might check your potassium levels and use another method to verify your salinity / recalibrate your refractometer.

 

[tymo92]

The acros STN’ing from the tips does sound like alk burn/burnt tips. This is normally caused by low nutrients and high alk (+9 dKH). In my experience, an alk of 7.5 dKH wouldn’t cause this, but it’s possible. Was your alk higher than this at some point? Sorry if I missed this, but do you dose nitrogen and phosphates? Do you dose amino acids or any other coral food?

If it’s bacterial, you can try an iodine dip. If that doesn’t work, you will likely need to treat with antibiotics in a separate tank.

Let’s see what Randy or someone else says about the copper. I think 0.018 ppm might be pushing it. From what I remember, Randy’s copper was somewhere between 0.01-0.015 ppm. I’ve always been told 0.02 ppm and above causes issues. Are you dosing copper or using a product that contains copper? Any metal fittings or metal stand? I don’t think it would hurt to run cuprisorb to be safe.

Ok, it’s probably not the RO water then.

Alk was around 8.2 when this all started so I lowered down to 7.5 thinking the same thing on burnt tips… I dosed nitrates early on until I got to the 4-5 range, and am still intermittently dosing phosphates.

No idea where the copper is coming from. Checked for any metal in or over the tank. I only dose kalkwasser and water changes (no trace addition) so wouldn’t think it’s from that.

 

[tymo92]

You might check your potassium levels and use another method to verify your salinity / recalibrate your refractometer.

Potassium checked on 2 ICPs and it was normal. Salinity checked at home on calibrated Hanna digital and handheld refractometers which matches the ICP salinity. So it’s not that.

 

[CHSUB]

Low nutrients

NO3 5ppm
PO4 0.02pp

2 ICPs did not flag anything particularly abnormal other than low/zero phosphates, and 0.018 ppm

Your nutrients are no where near low….look for another problem, increasing no3 or po4 will likely make the problem worse or increase values of pollution you are not testing for.
For example my no3 is many, many times lower than yours and po4 is about the same. ICP shows my po4 @ 0.008 ppm. This new thing of blaming low nutrients for everything is getting ridiculous. This advice is likely coming from inexperienced hobbyists or people misunderstanding some published ranges.

 

[tymo92]

7 Months in...my uneducated opinion is that its perhaps too early for SPS. I struggled to keep them till i basically hit the 12 months point.

I know others say and have great tanks that do otherwise...just my experience

I figure there has to be some underlying reason for “tank too new”, like unstable parameters, lack of bacterial diversity, low nutrients, etc. The strange is these frags were all growing and coloring up great just a few months ago (some added as early as 3 months from tank start). I should add that coralline is fully encrusted on all rock surfaces by now.

 

[Naturalreef]

Po4 at .02 doesn’t give you any buffer for test kit variation. You could be running at 0 or you could be running at .04. I try to either keep my nutrients with a buffer to compensate for test kit error, or I dose something like tropic Marin plus np that supplies nutrients and feeds coral via carbon dosing continuously so I know they are receiving nutrients.

If I see stn, it’s almost always low nutrients for me. Also look into keeping dragons breath macroalgae, either in your display or a refugium. Through studies, It releases compounds in the water that prevents pathogenic bacterial mats from forming aka rtn/stn.