Sps stn help!!

[addictedreefer]

So I tried telling myself it was just a couple of colonies being idiosyncratic, but it has now become clear that my 210 SPS tank is undergoing a generalized STN event. It started over a month ago when I noticed that the tissue on my green slimer was slowly dying away from the base up (very slowly, maybe an inch every one or two weeks). At first all the other colonies looked great, but in the past week or so I have noticed some gradual stn on many of the other colonies.
I am very perplexed. All colonies look 100% on the area above the dying tissue, with full polyp extension, color and even growth!! Also, there are still a good number of colonies that are not showing any ill effects at all. Also, all LPS, softies, clams, and anemones (including a rapidly growing blue s. gigantea) are doing very well. However I am afraid that this problem is not going to just go away as I have lost about 20% of the green slimer, and the other colonies affected are dying little by little.
I have ruled out pests as I can not see any flatworms or red bugs. My water parameters are as follows:
Temp: 77 (constant all day and night with a chiller)
SG: 1.026
PH: 8.3
CA: 530
ALK: 8 dkh
MG: 1350
NO3: 0
Phos: 0
Please help me out as I have been racking my brain about what is going on.
One possibility is flow. I have 2 Vortech MP40s running at full power on reef crest random. Perhaps the growing colonies are obstructing flow?? Any help/suggestions would be appreciated.
-Vic

 

[Jeff.:P]

might not be the cause, but your CA is a bit high.

 

[sciknen]

Could red bugs cause this? Knock on wood its not.

 

[stingythingy45]

What are you using to test alk?
I know from experience as well as others here that some test kits will go bad after a few years.

 

[addictedreefer]

test kit is elos, and its only 2 months old, so I doubt that's it

 

[pillowfish]

If it is staying localized to SPS I would look again at the possibly of redbugs, from the sounds of what you are describing it would seem quite possible. If you can get a macro shot of some of the colonies or corals in question that would help as well. Maybe try bringing your water to a local LFS to have them test it against your results for reassurance as well. You can also maybe help out the situation by fragging the corals above the receded tissue ensuring that you cut up high enough to get healthy tissue.

How large are the colonies in question? I would look at each one quite closely with a magnifying glass, if no redbugs then move on to other possibilities. Have you made any changes to the system recently?(ie, different salt, new additions, dosing for something for the first time, etc...)

 

[Blueflu1]

I am having the same problem. Some STN on my two large BN colonies. My orange cap is getting pale and some STN on my Neon Candy Cane. All my parameters are great. I started running carbon again and doing more frequent water changes. It has slowed or stopped.

 

[Ronnie]

I think starting with question can help you. It seems that you know your parameters so lets start with the most causes of STN problems.
1. Have you tried something new in your tank AKA GFO, vodka or dosing something to bring nutrients down ect, ect?

2. Next would be PH. Big problem PH at night is different then during the day as you know and oxygen depletion is a good cause (do you run a ventless heater in the house)?

3. Remember if you are experience death it is something that changed in your system or added to it only you can answer these questions.

Good luck, Hope this helps and I know how it feels to loose sps corals. If you want you can PM me and I maybe to help with more.