RTN or Not?


Premium Member
Okay, how can you tell the difference in RTN or if the tissue at the base of a coral is simply dying naturally from being smothered by it's own new growth?

I have a decent sized acro colony (larger than a softball) which has been doing great for years. As of a year or so ago, I noticed that the base was dying back a little because the new growth had completely blocked out its light and most of its flow. This has to occur in the wild as well so I thought nothing of it.

But I just noticed that a whole branch just RTNd in the last few days. It is lower on the colony and not near the new growth. Im not seeing any RTN on any other corals.

Should I be concerned? Any advice? Do you need to know any more information? Here is a link to a thread with a lot more info on the setup. ---> My 50 Cube
RTN will happen overnight, taking out a whole coral.

It's quite normal both in the wild and in our tanks for an Acropora to shade itself and have a lower branch die.

hey reefwaters, i was looking at your thread and i was just wondering how you like your hammy 14k? do you get good growth? i can see you have good color.... standard electronic ballast?
nemofish2217 I really like the Hamilton 14K. I had a 10K XM and it was a little too white IMO. I still would like to try the 10K XM with 2 more VHOs though. The 14 gives a very crisp blue with the VHOs on. It is still pretty white without the VHOs on. Yes, I would say I get great growth.

joetbs Im hoping that the one branch finally stressed out too much because of the lack of light and that it wont spread through the coral. The tips have been growing extremely fast in the past few weeks and the old growth has much better polyp extension and color than ever before.
I concur, nice tank. I wouldn't worry, it is natural. Especially in a tank like yours :D