Help with STN issues....perfect tank parameters....established reef

Lousybreed · Mar 28, 2020

First off this is affecting like 2-3% of my corals. I am diligent in inspections and I have just noticed a strange "trend" in some of these corals. I am having a very slow recession mainly on the dimly lit side of the coral. And it is recessing very slowly. Like 3mm per week. On some other corals this might move at only 1mm per week. I currently have two colonies that are going much faster ( RR Pink Floyd and PacMan) but oddly enough secondary colonies of these (in the same system!!!) are doing just great. here are my tank parameters:

600 gallons total, 6 tanks total connected to the same sump.
Par for acros: 1,200-400
Lighting is mostly hybird (MH and LED, T5 and LED, a couple of tanks are T5 only. The LED lights are light bars only. Nothing fancy.
Circulation is what most would consider "high" but not direct blasting.
Red Sea regular salt is used.
Inverts such as snails and shrimp are doing great.
Softies and LPS are doing fine.
Alk: 7.0-8.0 95% of the time. Right now it is at 8.3.....in a 600 gallon system it takes a long time to change (max 0.1 per day). Alk is never outside of 6.5-8.6 (over the course of a full year).
Ca: 450
Mg: 1380
NO3: detectable around 0.5
Phosphates: 0.10-0.15
Zero ammonia or nitrites
I use carbon 1 week out of every 4 weeks. If i change something in my tank (new wavemaker, new plumbing, etc) I will run carbon for a week. Incase there is some residue on it.
My RO/DI water is around 1.0-2.0 TDS
95% of my corals are growing at 0.5"/month on their tips and are rocking! color and growth are killer.

Before we go down the path of pests: I have a QT tank I use for everything. I have a 3 dip system i use for all incoming coral that takes over 3 weeks to complete. I own inspection glasses and inspect all my corals and the left over of my dips. Every month I pick 5 random corals and dip them to observe what dies. I look at them under a microscope for positive ID.

So more on that Alk....it has gone up recently from 7.7...and my Calcium Reactor has been dead constant: 160ml/min and pH of 6.45. So I do know that there is "stress in the water". The corals currently affected are: green slimer, rr pink floyd, pacman, and upscales microlados, and a tich on my GARF bonsia.

Could this be bacterial? Any other ideas? Any suggestions? I am very proactive on this so I have caught this early.

xxkenny90xx · Mar 28, 2020

Phosphate seem a bit high. Are they always stable between that range or have you been battling phos? I'm also not crazy about your monthly dips, seems like unnecessary stress.

xxkenny90xx · Mar 28, 2020

Also, I'd like to see pics of your system, it sounds awesome...

drawman · Mar 28, 2020

Just as a start. Do you generally get 1-2TDS post DI? Has it been a while since you've changed filters including DI. Does your tap contain chloramines?

Also how long has your system been running? Is this STN happening on mature colonies or frags?

Graffiti Spot · Mar 28, 2020

Yea some people have issues when their tds shows readable numbers.

Lousybreed · Mar 28, 2020

drawman said:
Just as a start. Do you generally get 1-2TDS post DI? Has it been a while since you've changed filters including DI. Does your tap contain chloramines?

Also how long has your system been running? Is this STN happening on mature colonies or frags?

Our community does not use chloramines, I have talked with the head of our utility dept. I change DI when it gets above 3, I have TDS monitoring in several spots to watch my system. HOWEVER being said, I have tested my RO only water with ICP and undetectable for everything besides minimal calcium and mag. I also use FOUR carbon filters before my RO units...I am going to call again about chloramines just to be safe, to be fair I asked and tested over a year ago, things could have changed.

Lousybreed · Mar 28, 2020

xxkenny90xx said:
Also, I'd like to see pics of your system, it sounds awesome...

xxkenny90xx said:
Phosphate seem a bit high. Are they always stable between that range or have you been battling phos? I'm also not crazy about your monthly dips, seems like unnecessary stress.

yeah phosphates are normally high, I do not use any type of phosphate removal. I do my monthly dips with potassium chloride which is relatively easy on corals.

AJsReef · Mar 28, 2020

If you're using a QT method before moving frags to the main system why would you ever need to dip them once they have made their way over to the display?

Lousybreed · Mar 29, 2020

AJsReef said:
If you're using a QT method before moving frags to the main system why would you ever need to dip them once they have made their way over to the display?

to be proactive incase there is an issue. I only dip 5 a month. I have over 500 corals in my system. When you have a large system you only know if you have a pest when its too late.

PatW · Mar 29, 2020

I had STN myself. My parameters were very close to yours: Ca 450, ALK 7.8, nitrate 1.5 ppm, phosphate .03 ppm. The STN hit my acropora only. It started at the base usually in the shade and advanced upwards. Took out most of them. I had used dry rock, ammonia and Dr Tim’s to cycle my tank. My acropora had been flourishing and I had some huge colonies. It wiped out most of my stock. I added a series of different supplemental bacteria cultures for reef aquaria. And the STN went away. I have read that some people think it is bacterial. So going with this view, the added benign bacteria squeezed out the pathogenic bacteria. My acropora are flourishing again as are new frags that I have put in.

I am not sure that the added bacteria did it or not. But you could try it.

Bacon505 · Mar 29, 2020

It would be helpful of you provide pictures so people can observe and chime in on the issue. Parameter is only 1 variable.

jda · Mar 29, 2020

What are you having STN? It could be totally normal to lose a few acropora every now and then if you are not keeping NSWish water. If you are losing some tougher ones, then OK and do not worry about it... but if they are easy stuff, then dig in more.

For example, the vast majority of my acros would not care about P of .10 to .12, but my Purple Monster and some other smoothies would not be real happy about it. Neither would a few of my Spaths or Soli. Most of my tenuis, valida, tables, etc. would not care at all.

I guess that my point is that not all acros are the same, so if you can talk about actual types/species, then this might help. The only thing that I have work for ever coral is NSW type parameters, but this is too hard for most people so they live with the small percentage of death that comes from not having this.

If is is just dimly lit places, then get more light or move the corals.

CoralWealth · Mar 29, 2020

You should really post some pictures of the affected corals and also the others that arnt, I think it will help us see what you are talking about.

Lousybreed · Mar 30, 2020

Tomorrow I will! Thanks guys for the tips. I will get back to you with pics and more information.

ocncheffy · Mar 30, 2020

Following as I've had this same issue. I think I've resolved it due to a low alk of 6.5dkh. For me, certain colonies would STN from the bottom-up, and others would have burnt tips. My alkalinity is sitting at a rock solid 7.8 via Hannah checker, and things are growing/healing.

Lousybreed · Mar 30, 2020

jda said:
What are you having STN? It could be totally normal to lose a few acropora every now and then if you are not keeping NSWish water. If you are losing some tougher ones, then OK and do not worry about it... but if they are easy stuff, then dig in more.

For example, the vast majority of my acros would not care about P of .10 to .12, but my Purple Monster and some other smoothies would not be real happy about it. Neither would a few of my Spaths or Soli. Most of my tenuis, valida, tables, etc. would not care at all.

I guess that my point is that not all acros are the same, so if you can talk about actual types/species, then this might help. The only thing that I have work for ever coral is NSW type parameters, but this is too hard for most people so they live with the small percentage of death that comes from not having this.

If is is just dimly lit places, then get more light or move the corals.

I am having problems with my smoothies. My Pac-Man just bit the dust. I have some of the colony still alive but it’s not looking good. My favorite green smoothie is going too. Upscale Microlades and the good ole green slimer are having the slow STN from the base in one tank. Not the others. My Pac-Man in my other tanks are doing well too. Come to think about it, it’s my DT that is having the issues. But again they are all connected to the same system.