Acropora showing small spots of skeleton, STN?

[Reef_Crasher]

A bit over a month ago I got my first Acropora (booberry) frag and it was doing pretty well in my Nuvo 20 for the first three weeks. Though in the past several days, first noticed Oct 7th, this frag started showing spots of skeleton at the tips of the Corallites. The day before I do recall noticing a small white ring forming around the base.

(image above, this was taken Sep 24 a bit over 2 weeks ago. Parameters recorded that day: pH 8.2 Nitrate 2.5 dKH 10 Calcium 460)

When I noticed the skeleton I did some testing and noticed some parameters were low though the major thing that stood out was that the water temp was at 75°F. I usually keep the tank at 78°F but had to turn the heater (Eheim Jager 50w) down during the summer so the temperatures could have dropped even lower when nights started getting colder. In the end, I ended up doing a 33% water change in the end to also replenish some of the parameters.

(image above, this was taken Oct 7. Parameters recorded that day: Salinity 1.025 pH 7.8 Nitrate 0.2 dKH 9 Calcium 440 Magnesium 1280)

That night after the water change the acro looked a lot happier with the polyps more extended though you can see where the skeleton is exposed better now. I also turned the heater up a bit though started to suspect the heater possibly not being as consistent for the colder nights.

(image above, this was taken Oct 7 later that night)

The water change might have raised the parameters a bit too rapidly so I was a bit worried about that, though for that day and the next I didn't see any more skeleton get exposed. During this time I also picked up an Inkbird UTC-306A temp controller to make sure temperatures were a lot more stable.

(image above, this was taken Oct 8. Parameters recorded that day: pH 8.2 Nitrate 0.2 dKH 10)

As I started to think things might have slowed down on the 10th I noticed another spot of skeleton appearing so I ended up doing another water test. At this point I wasn't sure why things were still slowly declining with this specific acropora. Parameters and temperature looked fine and all my other SPS (Montipora digitata, Plating Montipora, and some Seriatoporas) have looked fine and even healthier the whole time.

(image above, this was taken Oct 10th. Parameters recorded that day: Salinity 1.025 pH 8.2 Ammonia (undetectable) Nitrite (undetectable) Nitrate 0.2 Phosphate (undetectable) dKH 9.3 Calcium 450 Magnesium 1320)

For now I'll keep maintaining parameters to be as stable as possible and see how tings go. Today, I did move the frag a bit further from the light closer to it's original location and testing results were quite similar to yesterdays. I also added activated carbon that I'll keep for a couple days just in case it could have been toxins from my soft corals (Palythoa, Nephthea, and Zoanthids). This is the first time I've experienced this so I wasn't completely sure if it is STN cause I haven't seen images of STN like this before. As of now my current suspicion is that it was a mixture of the dropped parameters then the sudden temperature drop due to the cold nights that might have pushed the acro over the tipping point of stress though if anyone has thoughts of what might be coursing this, I'm open to any ideas.

(image above, this was taken Oct 11th. Parameters recorded that day: Salinity 1.025 pH 8.2 Ammonia (undetectable) Nitrite (undetectable) Nitrate 0.2 Phosphate (undetectable) dKH 9.1 Calcium 440 Magnesium 1320)

 

[mdb_talon]

It does not look like stn to me. At least when i have seen it it will always start with the skin....and the polyps are last thing to go.

I cant say that it is the reason, but i dont think you are doing it any favors with very little nutrients. It looks like nitrayes are consistently .2 and phosphate undetectable?

 

[Reef_Crasher]

It does not look like stn to me. At least when i have seen it it will always start with the skin....and the polyps are last thing to go.

I cant say that it is the reason, but i dont think you are doing it any favors with very little nutrients. It looks like nitrayes are consistently .2 and phosphate undetectable?

Yeah, this tank being a bit too good at removing nutrients and is one of the first things I've noticed. In fear of possibly getting dinos cause I've had them in the past, I actually started dosing NeoNitro 1.5 ppm daily which was why the polyps in the first picture looked really good and why nitrates were at 2.5 ppm. In the end though I reduced it to 0.5 ppm daily a few days after cause how quickly diatoms in the tank built up which is why nitrates dropped back down again. Though thinking about this now, could also be a reason for what's going on, so I'm probably going to increase Nitrate Dosing slowly again to see if it changes anything along the line.
As for Phosphates I had a one of those API test kits which are pretty hard to tell, the tests say 0 Phosphates but I don't really trust it so fortunately I do have a Hanna Phosphate ULR tester coming in soon so hopefully I can get official results in on that soon.

 

[Reef_Crasher]

Small Update:
Just tested with a Hanna Phosphate ULR checker and reading 0.03 for Phosphates which seems to be alright from what I have been reading.

 

[Dono]

I have a bb acro tank and suffer from chronic low nutrients. When I bottom out and it happens occasionally, my acros get spots of exposed tissue and in severe cases the smaller/newer branches will "melt". Start dosing aminos as a nutrient supplement.

I stopped growing macro algae because of this and went to a cryptic sump, which seems to help. Additionally, I found a huge clump of hair algae in my overflow that was consuming a ton of nutrients. Be wary of hidden "nutrient sinks"

 

[Dono]

edit: accidental double post

 

[ChaosAquaculture]

I would try to get nutrients especially phosphates uo tk the .06/.08 area if possible. The skin won’t melt in that way anymore and all your coral overall will be happier - kali

 

[Reef_Crasher]

I have a bb acro tank and suffer from chronic low nutrients. When I bottom out and it happens occasionally, my acros get spots of exposed tissue and in severe cases the smaller/newer branches will "melt". Start dosing aminos as a nutrient supplement.

I stopped growing macro algae because of this and went to a cryptic sump, which seems to help. Additionally, I found a huge clump of hair algae in my overflow that was consuming a ton of nutrients. Be wary of hidden "nutrient sinks"

I can't tell if its because of this cause I've stated dosing it yesterday but I have started dosing Reef Energy AB+ and Increased NeoNitro dosing from 0.5ppm to 1ppm a day, but today things seem to have stopped getting worse. As for phosphates, the only large nutrient takers in the tank are diatom algae on the glass which has recently started growing back faster since I've been dosing NeoNitro.

 

[Reef_Crasher]

I would try to get nutrients especially phosphates uo tk the .06/.08 area if possible. The skin won’t melt in that way anymore and all your coral overall will be happier - kali

Unfortunately I don't have anything to raise phosphates artificially, but I will try feeding a bit heaver to see if that increases my phosphates/nutrients in general over time.

 

[The Opinionated Reefer]

AEFW bites?

 

[Reef_Crasher]

AEFW bites?

Doesn't seem to be AEFW, I have a generic Acro next to it which is doing surprisingly fine, will say though things are doing better but will post an update sometime this week.

 

[C. Eymann]

9dkh with 0 Po4 and near 0 nitrate could be the cause/ the spotty start of burnt tips, esp in higher PAR.

 

[Reef_Crasher]

9dkh with 0 Po4 and near 0 nitrate could be the cause/ the spotty start of burnt tips, esp in higher PAR.

Oh, interesting. This is the first time hearing about alk/PAR being a factor. Taking a first shot of this but do acro become more sensitive to higher par in a ULNS with alk around the range that I'm getting?

 

[homer1475]

Think of it this way......

Nutrients help skin grow. ALK, CAL, and MAG and light(food for zoox which churns out sugars for the coral) make bone grow. If your high in one area(bone growth with high ALK), the bone grows so fast the skin cannot keep up, and you end up with "burnt tips".

So in essence with high ALK and light your growing bone super fast, but the skin without nutrients cannot keep up.

Typically with low nutrients, you want more natural sea levels(7DKH, 420CAL, 1350MAG), as opposed to elevated levels with elevated nutrients.

 

[Reef_Crasher]

Think of it this way......

Nutrients help skin grow. ALK, CAL, and MAG and light(food for zoox which churns out sugars for the coral) make bone grow. If your high in one area(bone growth with high ALK), the bone grows so fast the skin cannot keep up, and you end up with "burnt tips".

So in essence with high ALK and light your growing bone super fast, but the skin without nutrients cannot keep up.

Typically with low nutrients, you want more natural sea levels(7DKH, 420CAL, 1350MAG), as opposed to elevated levels with elevated nutrients.

Oh, that really makes sense from what I recently just experienced. Two weeks ago I came back from a 4 day trip where I couldn't do any manual dosing of CAL and MAG (had a doser doing ALK which kept DKH at 9) . When I came back all my SPS were doing surprisingly great. Test results from that day were 9.0DKH, 425CA, 1260MG, 0.5N03, and 0.03P04. Ever since till 6 days ago since I've reached the goal, I've been trying to raise it back up to 450CA and 1360MG, and today unfortunately things SPS wise are starting to look downhill again.