Need help with challenging slow STN event

Decadence

New member
I have been having some slow-moving STN for a month or so now. I didn't think much of it until a couple weeks ago when it popped up on some corals which didn't make any sense. It all started on that large, new millepora colony that I added a couple months ago. I figured that the rapid change in parameters was finally catching up to it and it would subside. In the last couple weeks, my large tyree tricolor, my large valida and large blue tipped teal stag have all started. These corals have all been with me for a little while and I have no explanation as to why they would be going. All of the corals experiencing problems are large colonies.

It's hard to say when it all started because the millipora started well before any of the acros did. The millipora did not have any significant events surrounding the start of STN. I have made some significant changes between then and now:

Light - I raised my lights and swapped drivers for dimming control. All-in-all, the corals have been getting less light. This was in an attempt to color up a lot of my corals which had lost color over a long period of time. It worked for most corals.

Nutrients - As another measure to color up corals, I removed my GFO and stopped syphoning detritus for a few weeks. I was hoping that the additional food in the system would help with coloration but at the end of the day, it just meant that I was cleaning my glass twice a week instead of once a week. I syphoned the detritus and blew out all of the rocks and then put in fresh BRS GFO.

Salt brand - This may be one of the key contributors but I have done the switch slowly in my opinion. I was using Kent before which was putting my potassium levels into a toxic range and gave me the symptoms of an overdose (same symptoms as low potassium). It was making my magnesium uncomfortably high and made me have to dose alkalinity supplements by hand to try and match alk to calcium as it was hovering my calcium around 500ppm, also uncomfortably high. This previously never made a difference to me until I started doing large weekly water changes as opposed to using a turf scrubber and doing them every few months. After realizing I couldn't do this with Kent, I switched to Instant Ocean and did a 20% water change every week to balance out the levels of everything slowly. Regular Instant Ocean is very close to natural sea water levels on all counts and I have a large bank of dosers to help meet the needs of my heavily stocked SPS tank once I get everything under control.

Algaefix - I successfully completed a month-long round of Algaefix, beating out ghost algae. With the ghost algae, it also knocked out my entire pod population. My experience thus far with the product has been that it is 100% reef safe when it comes to corals. I have been on a maintenance dosage for a couple months now, only dosing on Sundays after lights-out.

Pests - I have had just about everything but I cannot for the life of me find any known SPS predators in the tank. I would think that it is AEFW but there are no signs and the recession does not look like the commonly seen "bites". I had red bugs which mysteriously vanished upon the introduction of a six-line wrasse who pecked at acros all day long until they were gone. I haven't seen them since. When the pods all died, it gave rise to a plague of mini brittle stars. Wherever I see tissue recession, I see stars bundled up in the white skeleton. I have also seen planaria flatworms, lots of them. These are known to not be predators but they are toxic when they die. I have considered that the issue may be the numbers planaria as more flatworms will mean that more are dying regularly.

I have taken a few steps to try and combat this issue but I am at whit's end. Thus far, I have purchased all new test kits to confirm that I do not have any false readings:

PH 8 at night, 8.3 during the day
SG 1.026
Alk 7.7-8dkh (has crept up to 8.5 duh due to the slowed SPS growth over the course of a week)
Calcium 440ppm
Mag 1440ppm
Phosphate <0.015ppm
Nitrate <1ppm
Potassium 410ppm (down from 440ppm)
Boron 5ppm

  • I have discontinued the use of all of my dosers. The only things which I was dosing which I do not have test kits for would be iodine and iron, both of which I was dosing very small quantities of. None-the-less, they are all offline now until the problem is resolved. I will bring them each back online slowly so that I can test and dial each in and watch the results in my corals.

    I ran a polyfilter and it did not change any abnormal colors other than what a regular filter pad would. I was thinking there may be a few small flakes of metal leaching something into the tank from the sump. When the polypad was inconclusive, I decided to drain the whole sump and clean all of my equipment, then shop-vac the whole sump to get a fresh start with all of the sediment.

    I'm relatively positive that the issue is not stray voltage, but just in case I changed all of my submersible pump motors. The display has a ground probe in it between the overflow and the return outlet but I also only use vortechs in the display and there are no cords. I put my heaters on a GFI powerstrip so that any voltage leaking from them would turn them off and the RKE would send me an alarm.

    I calibrated my PH probes and refractometer and tested the output of my vinegar vs. what it was programmed for.

    I cleaned all of my vortechs to ensure that they were still delivery awesome flow. This was a concern being that all of the colonies showing STN have been large. There are three MP10s and one MP40 on the 90 gallon display.

    I have kept up with water changes at 20 gallons a week, slowly bringing all levels to NSW and removing potential contaminants.

    I have set up systems to double-check other systems and avoid disasters. During this whole time, I have had a kalk overdose due to my skimmer overflowing from a clogged air inlet. I put a float switch inside of my reservoir to turn off the skimmer in the event that it overflows. It will also turn off my ATO if my PH gets above 8.4. I put battery back ups on the whole system in case their are power spikes or flashes causing any problems with equipment.

I am out of ideas.

All that I can still think of to try is a harlequin shrimp to eat those pesky mini brittles and some flatworm exit to rid my tank of planaria flatworms. If these don't work, I may attempt a 100% water change and clean all of my rocks with my fish all in quarantine, an obvious act of desperation.:(
 
One parameter I find most of us often overlook-Ammonia. Some of my sps frags started out fine then slowly STN from bottom up and sometime from top down. Just a guess but worth looking into IMHO.
 
One parameter I find most of us often overlook-Ammonia. Some of my sps frags started out fine then slowly STN from bottom up and sometime from top down. Just a guess but worth looking into IMHO.

Thanks for the suggestion. I actually don't even own an ammonia test kit. I think I actually figured it out tonight. My RKE has been dosing 9.9ml of Algaefix every single day for the last month. I was shocked to find this out tonight when I was attempting to take it offline through the controller. I went in to double-check the programming to make sure it was all correct. I know for a fact that the settings were S------ when I put it in but it was SMTWTFS when I checked. I went in and changed it back, hit "save" and then went back into it and it switched back to SMTWTFS again! I don't know what is wrong with it but the doser will certainly be unplugged until it is figured out.

Until I see improvements, I will continue testing, diagnosing and doing water changes until I am certain that the issue is resolved.
 
Lets see some pictures to help us out. The corals your talking about could have been stressed from the red bugs for so long that now with all the sudden changes (even though there are less or no redbugs) they are finally stning? Is it only thoes few corals?
 
Lets see some pictures to help us out. The corals your talking about could have been stressed from the red bugs for so long that now with all the sudden changes (even though there are less or no redbugs) they are finally stning? Is it only thoes few corals?

I'll get some pictures up but I believe that the issue is resolved. Everything looks MUCH better today. The tissue necrosis seams to have stopped and any spots appearing dry look full. I also had terrific polyp extension.

As far as red bugs go, it has been a long time since I have seen one but when I did have them, even corals which were covered in them never showed any noticeable signs of stress. This leads me to believe that I didn't have a particularly harmful breed. I do believe that sudden changes have had an effect on the corals and may be partially responsible for some of the tissue necrosis from added stress.
 
Algaefix is not 100% safe. It killed or severely hurt some softies in one of my tanks a few years ago. I would not trust it with SPS.
 
That's good I hope you figured it out! I know you keep a beautiful tank, even with the red bugs! I killed half my corals changing too much at once, so it's kiss for me for a while. I still want to see some pics!
 
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