RTN occuring in my 18 gallon!


New member
I've also posted this in the SPS forum, but since I own a "nano reef", I figured it might be of interest here, as well...

I've been experiencing RTN recently, and I have no indication about why this is happening. Allow me to describe what has happened up to this point:

I purchased a few frags about a month or two ago, and one of them was a VERY cool light purple acro with nearly fluorescent green polyps. Three days after I had this in my tank, it went through RTN, and I came home from work and found a white skeleton in my tank. A few days later, it took another of my new frags. A couple weeks down the line, one of my long established colonies also succumbed. Shortly thereafter, I bought a few new frags, and some of them were acros. I picked up a very small frag similar to the first one above that went through RTN, and yes, this one peeled a few days ago. And it doesn't appear like I'm "out of the water" yet, so to speak. My longest-established acro colony, a less than impressive tan acro, has been slowly but surely losing tissue around its base for the past two nights. I am expecting to see another dead coral anytime now.

The strange thing is that my water parameters are all very good, and look like the following:

Specific gravity: 1.025
pH : 8.2-8.3
dkH : 10.2
Calcium : 390
Nitrate : 2.5
Phosphate : 0.03

The SG reading comes from a refractometer, and the other readings are brought to you by Salifert. And it's strange that the colonies are dying one by one. Pretty soon, I won't have any "regular" acropora in my tank, and it'd be nice to know why! My very unscientific impression is that this is the result of something contagious that is spreading through the tank.

You might want to check for Acro eating Flatworms. There is a sticky thread at the top the the SPS forum on how to detect and treat.
Thanks. That's something I never even suspected. I'll look at my acros VERY closely tonight. This SUCKS! But if I have them and they end up wiping out all of my colonies, I'll let them die off for quite a while before I add any more acros to the tank :(