coral bleaching

I was reading over another post in this section and read a lot about corals bleaching. I had some zoas that where green and some that where pink. The pink ones stayed super bright but the green zoas eventually started turning white in the center. Is this due to bleaching? I really didnt think it was close enough to the top to cause this. My lighting is 4x55w t5 and 2x65w pc for actinics on a 75 gal.

note: I have over hauled the tank since then and dont have any pics I am just trying to get information for the future.

 

It has been my experience that zoanthids shift coloration in response to lighting rather than bleach. I get the same whitening to the center when I place my zoanthids too high in the tank. It takes a lot for them to actually lose zooxanthellae IME, like totally shading, but intense lighting is supposed to make them speckle more, or so I have been told.

 

While we are on the subject, I have a closed brain coral that turned white around the edges after I added to my tank. It was turning white pretty quickly but then stopped and most of it is perfect color.

Will the white part ever re-color or is it dead?

Thanks.

 

If the while part is tissue than yes it can re-colonize with zooxanthellae. If the while is skeleton than no, new tissue may grow over it though. Unless something drastic has taken place like a over dose of alk or a crash, coloration shift and changes in zooxanthellae populations, can take along time IME.

 

I was referring to, too much light causing the coral to bleach. Is it not the same thing?
Is there a method of actually bleaching?(I know some how they wrongfully do this with anemones.)

 

Bleaching to me is when the zooxanthellae leave the zoanthid. They become stark white all over not just the center. A coloration shift to me is when you see a darkening or lighting of a coral in response to lighting or parameters.

I would just move them down. Or frag the ones with the white center,place the frag lower down and keep the pink ones near the top where they are currently happy.

Not all zoanthids live in the same illumination zone, so what is good for one type might cause a problem with another type.

 

Thank you. Unfortunately I had to shut my tank down and am now starting it back up and doing TONS of research. I just wanted to know what to do if it happens again. You can see my new tank set up in the thread
http://www.3reef.com/forums/i-made/setting-up-tank-need-some-advice-109637.html

 

Oh yeah I remember this thread. I really like what you did with the walls, very nice.

 

Thank you!!!
I just put in the sand and got the reactor and rox 0.8 today.