A question regarding stylophora growth

[kattz]

I have a huge green stylophora in my tank.  It's very healthy.  However, I looked at the absolute bottom "trunk" and there are no polyps on it; it's shaded from the light.  There's no polyps deep within the coral on the branches that receive little or no light.  Is this normal or is this STN?

[CoralBeauties]

Take a real close look to see if you can see any color at all.  If it is fresh stn it will be pretty much bleached white and should see almost a divider line between the bleached part and where it meets good tissue.  Most of my stn issues have always been from the bottem up on most all of my corals and I have been able to clearly see the divider line between the stn and good tissue.  Most of my larger corals dont have any polyps or color on the underside or deep within the coral.
Jeff

[Ashlar]

No polyps, or clear polyps? You'll frequently see colorless polyps deep in a branching coral or on the heavily shaded base.

[Neogenesis]

Stupid question....but what's STN short for?

[Ashlar]

STN - Slow Tissue Necrosis, as compared to RTN - Rapid Tissue Necrosis.

[Neogenesis]

Thanks for the clarification!!!

[SapperChris]

What causes stn and rtn? I've had this problem before with acro and never could figure it out.

[Ashlar]

What causes stn and rtn? I've had this problem before with acro and never could figure it out.

If you could figure that out, every reef forum on the net would be abuzz for a month.

Lots of theories, but no answers.

[CoralBeauties]

From my experience with my tank and my corals anytime I have seen stn it has been an issue with alk. levels being off and or lower ph levels.  If I notice a coral starting to stn those are the first 2 things that I check and one or both are usually out of the normal range.
Jeff

[starfishprime]

I say normal