STN

[sen5241b]

A month ago I did a water change and the salt was not fully mixed. Pieces of slat fell all over the corals. Should have let make up water sit overnight. I blasted the salt off the corals but the damage was done. I come back from Asia (ironically after visiting the Coral Triangle, see pics in scuba forum)  and the STN has spread across my LPS. I noticed some STN before I left. My trumpets I've had for 9 years have died back 75%. Blastos and Rose Chalice look bad. Strangely, some LPS like alien eye chalice are fine. What is the solution here? I'm thinking cut out dead corals, dip iodine and big water change. Help.

[Origami]

I think that cutting back past the dead tissue will give you a fighting chance here. The iodine dip is also reasonable as is the big water change. Then, of course, watch carefully. Some have had some success laying down a little super glue at the fresh-tissue edge of a cut. I guess the thinking is that it acts like a bandage that helps block the damaged tissue from infection. Take/make a few frags while you're at it as a safety measure. If you've got stuff that you really don't want to lose - take frags and distribute them around to a few friends as a sort of coral ark that you can go back to in case you lose the colony.

[sen5241b]

Is sudden salinity change a definite cause of STN? I'm still trying to figure out what caused this. I blasted the salt off the corals immediately so I don't think the undissolved salt itself was the cause. Tank doing much better. Cutting out infected but still half-alive corals helped a lot as did iodine dips.

[madweazl]

Unmixed and freshly mixed is fairly caustic as is a salinity change when it comes to SPS. I think the affects of salinity swings are way underestimated when it comes to SPS. 

[sen5241b]

I did not know that.

[Origami]

Is sudden salinity change a definite cause of STN? I'm still trying to figure out what caused this. I blasted the salt off the corals immediately so I don't think the undissolved salt itself was the cause. Tank doing much better. Cutting out infected but still half-alive corals helped a lot as did iodine dips.

A "definite cause"? I'm not sure that we know all the different ways that STN can be triggered or that a sudden salinity change can even trigger it. Certainly, a sudden salinity change can cause harm, possibly allowing an infection to take hold, which might then lead to STN being observed. Sudden and prolonged salinity swings may be just one of many causes of stress that can lead to STN or even RTN.

[Matt LeBaron]

Did you check your salinity after the change and then the next day? Not sure how much of your water volume you changed but if there was undissolved salt and it was enough of your total water volume you probably ended up shocking your corals twice, once during the change when the mix was still fairly caustic and then again as the salt fully dissolved changing the salinity of your tank a bit unexpectedly.

 

No one really understand STN or RTN well at all but keeping any change to our tanks gradual seems to be the best way to avoid it.