Mystery STN - Thoughts?

[Mark426]

I have dozens of Acro frags that are doing very well with excellent color and moderate growth. However... it appears that when several of them encrust the frag plug enough to contact my rock they have began to loose color at the base and start STN as seen in the photo. My parameters and are good (triton testing) and dead on stable. They get fed enough with poop and misc food like oyster eggs. No pests that I can find or bothersome livestock. I am beginning to think that there is something either in my Marco rocks or with the Two Little Fishes epoxy I mount them with. So....do you think that something in the rock or the epoxy could be the cause this. Others that are in direct contact with my rock and have no epoxy seem fine so I am inclined to think more of a possibility that it may be the Two Little Fishes epoxy putty. Have you had/seen anything like this or am I just grasping at straws. At a loss here.

ALK 8.4
CA 430
MG 1400
SG 1.025
NO3 - 0.0 or at time just detectable
PO4 - 0.01-0.02 (Triton and Hanna)
ESV Two Part
T5 Lighting and the coral in the photo gets 400-450 PAR for 9 hours
GFO and ROX Carbon (BRS brand) in moderate amounts run passively in sump

Edit: Trition tests show high Lithium and Tin like many others here.

 

[Fragman4]

I would say it is a pest. I use the same epoxy with no ill effects. Have you tried taking one out and dipping it to see if anything comes off? It is definitely odd that it only happens when they hit the rock though.

 

[jroovers]

I would lean towards , assuming you've eliminated everything else. The carbon and GFO - either too much or being refreshed too quickly... I had issues with base recession specifically with the high capacity BRS GFO, and I also found the carbon was a potential culprit, especially if I didn't rinse it very very thoroughly. I went back to the normal GFO (very very small amount) and got rid of the carbon altogether, and things were much better. The only other think I would consider is Alk swings.

 

[rovster]

I would lean towards , assuming you've eliminated everything else. The carbon and GFO - either too much or being refreshed too quickly... I had issues with base recession specifically with the high capacity BRS GFO, and I also found the carbon was a potential culprit, especially if I didn't rinse it very very thoroughly. I went back to the normal GFO (very very small amount) and got rid of the carbon altogether, and things were much better. The only other think I would consider is Alk swings.

This. Definitely looks like a water quality issue. Not saying your water is not quality, but something chemically about it is not agreeing with your corals. I agree with above, looks like either an alk issue or a nutrient stripping issue. The coral looks great except for the area of recession, which tells me whatever happened was something quick and short lived, in contrast to corals that over all look ragged which points to a more overall issue.

 

[Eastone]

Necrosis from the bottom up is a coral-regulated symptom of inefficient tissue in my experience, this can mean either poor light, low-no flow or poor nutrients. Considering your coral isn't a mature colony with shading and flow issues at the base I'd agree with the above posts and suggest that you're doing too good of a job with nutrient removal. It is my belief that we shouldn't ever need to permanently need to run GFO as it near-completely strips the water of PO4 which is very, very detrimental to SPS growth and health and can result in what you're seeing.

I would suggest slowly transitioning to another method of po4 removal such as a turf scrubber or aio biopellets while reducing your GFO volume by 1/4 every 4 days. Additional dosing of amino acids and dissolved food compounds such as KZ Coral Vitaliser or Red Sea Energy package would be beneficial too

 

[Mark426]

This. Definitely looks like a water quality issue. Not saying your water is not quality, but something chemically about it is not agreeing with your corals. I agree with above, looks like either an alk issue or a nutrient stripping issue. The coral looks great except for the area of recession, which tells me whatever happened was something quick and short lived, in contrast to corals that over all look ragged which points to a more overall issue.

I just now checked and my second Triton results were posted. I am almost positive its not an ALK issue though, must be something else. My home tests agree with Tritions and are stable both day and night.

You may be right about the nutrients. I am going to start slowly removing my GFO over the next week or so as my latest Triton showed zero PO4. Nitrates are not really detectable with salifert/red sea. I am going to try and ease them up until I can definitely detect some trace. Maybe they are starving despite my feeding.

 

[jroovers]

I think that is a good plan.

That said, I don't think base recession and any links to GFO and Carbon is due to starving... I think its due to some other mechanism. That is just my opinion though based on very anecdotal experience, so take it for what its worth. There is something with the carbon and GFO that can change the chemistry, parameters whatever that SPS are very finicky too (and impacts some corals much more specifically than others). With a bit more trace of both phosphates and nitrates, you're likely to see some richer colours, so could be a double bonus

 

[bigbuckdown]

Don't go by triton for your alk test. Your alk can change a lot from day to day if your not careful. I check my alk everyday sometimes twice if I'm messing around in the tank or calcium reactor. I suggest checking alk everyday to my friends keeping sps all the time since it's probably the most important parameters in our tanks. Takes 5 min a day to check and 23 hours and 55 minutes a day of no worries