Polyp Extension and coloration

[Scubajoe1]

Just a general question about Polyp extension and coloration.

I have several SPS colonies and frags in my tank. Parameters are very stable.

Alk- 9.5, Temp 78.5-79.1, Ca- 450, Nitrates- 1.5 ppm, phosphates 0.06 ppm, Mg- 1400 ppm.

I have polyp extension on most corals. I have one deep water smooth one (Coral B) that has no polyps to be seen nor never has. I have a second piece that also has never had any polyp extension but this looks more like a standard piece of Acro (Coral A).

Any idea what type this one is?

Also this seems to be light brown on the underside where it is not getting the same light at the top.

DO other people have corals without polyp extension and b) do you have corals that the underside is not really colored up?

Also does anyone know the name of coral B here?

 

[E46Twist]

I am not even close to an expert here but I will give info based on my own experience. I have monti caps, digis, and an unda and none of them have much in the way of polyps that extend you can see them but it is nothing crazy, these corals are all growing very fast and have good color so they must not be too unhappy. I have an acro that looks like coral B and again does not have crazy long polyps nor are they packed together. Now I do have a paradise birds nest birds nest birds nest that looks like a fuzzy tree when the polyps are all out. If you look closely with just actinics on I but you see some PE or if you put some coral good in the tank you will likely see it. If there truly is no PE I would think that would be a problem and indicate a problem but again I can only speak from limited experience from what I have kept.

Good luck and happy reefing

 

[Wsufan18]

I have several acros that never have polyp extension when the lights are on yet are growing with great colors. I sometimes shine a flashlight on them after the lights have been off for a few hrs and polyps are extended like crazy! Have you tried a flashlight after hrs?

 

[Scubajoe1]

I have but not on this Acro in particular. Will check it out when I get back home.

 

[scumbag_gli]

B looks like a Cali tort

 

[DiscusHeckel]

I have three smooth skinned acropora colonies in my tank: A. lokani, A. granulosa and A. carduus. They extend their polyps in the dark unless I feed my tank heavily during the light hours or add coral food, such as rotifers.

The first coral looks like Acropora tennis. I believe that I have exactly the same coral in my tank, which looks very "hairy" day and night:

 

[ReefBum]

What kind of fish do you have in your tank? Angles can nip at SPS polyps.