Slow Painful Crash...


Active member
So my 60 cube is about 2.5 years old now and has been going quite well the last year... Great growth. Good color... But recently I had some STN/RTN. I had another thread on it but I thought perhaps the title was not soliciting any interest so I started another thread.

I had about a month or so ago lost a colony of Strawberry Short Cake. Well more like a large frag... I thought nothing of it as everything tested well. A week or so later I notices some STN on my copps hoek colony, grape juice colony, two out of my three bonsai colonies and also my frogspawn looks limp on one side. I hadn't changes or added anything in months. I see no bugs. My LED lights have not changed. I did change out my GFO about a week after the first colony. But I added the same amount as always and had been running GFO from day one.

Then my Ultimate Stag melted in a day. I did manage to save a large frag, but it was a huge colony and made me quite angry. I took the GFO off line, began 20% water changes twice a week, and threw a small bag of carbon in the sump, just in case something needs to be filtered out.

It has been several weeks and I thought the necrosis had slown down but I really has not. My frog spawn looks worse but only on one side. Looks like it is getting blasted by a pump, but that frog spawn has been in the same spot for two years and has grown out of control. Nothing new on that pump either...

Today I took 80% of my copps hoek and dumped it in the other system to try to save it. I checked everything I removed for bugs and saw nothing.

Here are the parameters:

Nitrates 0-.02
PO4 undetectable
Alk 7.0 (where it always is)
Mag 1440
Calcium is up from 450 to 535 (See below)*
Potassium 460 (dosed weekly for 2.5 years)
PH 7.8-8.4
Salinity 35
Temp 78

I have backups for every test kit. I tested my refractor with an old hydrometer and they match. Tested my apex temp against a stand alone thermometer and they match. Apex PH against a test kit and they match.

I dose Phols XTRA daily (have been for two years) Brightwell AA (for two years as well). However I did notice a little Cyano so I cut back on these about a month before to just a couple times a week. But I doubt that is it. I also dose phols Coral Snow and MB7 to fight the cyano. It works quite well.

* I was putting my syringe from the coral snow in a measuring cup every night. These measuring cups I use to hold my water (including RO water) when performing my weekly tests. I think KZ puts some calcium in the coral snow because that's when my Calcium reading shot up. It also shot up on my frag system at the same time. Both systems are not connected so I am not sure how accurate that calcium reading is. Either way, it would not cause the problem and there is no precipitation.

I have a 1-2 inch sand bed and haven't really messed with it because my coral prevents me from syphoning it. I run filter socks and change them weekly.

Here is the strange part. I have great PE and my growth is out of control...



New member
"PO4 undetectable" <----- That is not a good thing for S.P.S. and may be the cause of your trouble.


Active member
It has been undetectable since day on so I would tend to think something else has changed...


New member
It has been undetectable since day on so I would tend to think something else has changed...

How many days are you going between glass cleanings? My po4 show undetectable as well but I know that if I go longer the 2 days without film on my glass that I need to start to feed more.

Maybe the amount that you're feeding isn't providing your colonies enough nutrients. It was enough when they were smaller but now that they've grown they need more?


Grizzled & Cynical
My experience with STN is that it is typically a light and nutrition problem. I get it a bit when the SPS colonies get too big and start to shade each other and themselves. Pruning back helps, as does ensuring the tank gets enough food input (in my case, a byproduct of feeding the fish). May also be that something is missing, maybe something not being tested for? Personally, I like to run alk on the high side; but you note that your tank ahs always been at 7. what are your frequency of water changes? Perhaps stepping those up for a while might help.

RTN seems a whole other kettle of fish. I've had it a few times and found that it spreads easily, so presumably it is some kind of bacterial problem? Perhaps running UV for a bit would help.


New member
Ever experience equipment failure of any kind recently. I had a reactor pump in my tank fail and slowly lost all stony corals. It tested perfectly on all parameters, did tons of water changes, but inevitably slowly lost all LPS and SPS. It was totally random and cyclical over 2 months before I restarted the tank. I strongly believe I experienced heavy metal poisoning from the pump failing. If you look in the literature on the effects of heavy metal poisoning on coral it is basically exactly what happened to me. Just a thought. Good luck.


Active member
I do water changes monthly, but have stepped those up in size and frequency since this started. I now do them weekly, but did 20% twice a week for two weeks.

I was considering running a poly filter to check for metals...

I have stepped up the feeding as well. Since a few were looking lighter. Since color recovery can take months, I will need to wait a while before I declare that successful.

I have seen "dark side" recession on my larger colonies. This is different for sure.

Thanks for the suggestions. I will take a harder look at all of these...


Active member
So now my Hawkins is stn'ing and my cali tourt has no PE. Other look great and growing fast.

Calcium 425
Alk 9.0
Nitrates 2.5
Salinity 35

Reef Frog

New member
I have struggled with stn on acros as well in an otherwise thriving tank. My research has also found that very high ALK (not your problem) or fluctuating ALK has been said to be a cause or at least a contributor. It's so frustrating as all the info out there seems to be highly speculative with virtually no authoritative information or solutions available. Good luck.


Active member
Thanks. Glad I have a backup system that is doing well but I am running out of room as I have been filling it with frags from the stn'ing colonies...


Active member
I would think it's not anything your testing for. Stray voltage or a rusty magnet coming apart?

I tested for stray voltage. a few millivolts.... For reference my frag system had 40 volts because of a bad pump and everything was thriving. Didnt even know about it until I got shocked...

I agree about the magnet. possibly a cracked pump or issue with the chiller. I am running a poly filter now to look for the color shift. I will wait and see on that...