[Dive_Master]

I have had this coral for about a year under PC lights and it grew to about 10 inches in diameter. Absolutely amazing. He is all the way on the bottom of tank (30 inches form the new MH 250 W. 10000 K lights).

Now, he will not expand and is changing its color from green to yellow. Are the MH adversely affecting the coral. He is not receiving direct light.

All water parameters are the good.

The lights are on for about 10 hrs now, but I broke him nice and easy starting at 2-3 hrs a day and then increasing it slowly over a period of a month. I noticed his condition about a week ago.

What can I do to change his condition.


The trumpet coral (another favorite) does nto like the MH lights, I had to move him away. He was thriving, multiplying under PC lights. I hope he survives.

It is interesting that we still do not know why this is happending, at least I do not know.

Thanks

[Reefland]

It's possible that it still needs acclimation to the MH lighting and action is required on your part. It's not just the photo period, but the intesity itself when the lights were/are on during the acclimation period.

It sounds like shading these corals a bit would be helpful while they try to adjust. There are methods described in literature about using pieces of screen in layers and removing 1 layer of screen weekly thus allowing more light to reach the coral each week, but this seems it would be difficult to set up. Another method would be to raise the lighting above your tank and slowly lower it to the desired height over the course of 1-2 months.

[Dive_Master]

Scott,

I think you were right. I put a small plastic (blue) filter above the coral and wow after two days it got the green color back and it is expanding. It expanded almost to the original size.

I will take a picture of it when I take the filter out so you can see how beatutiful this animal is. I did not want to loose him.

Thanks a lot for your feedback.

[Dive_Master]

Scott,

I moved the lights up to 15" above the water. Do you think it is enough. I think the 250 W are a little too big for a 75 gallon tank?

[Reefland]

250w are not too much for a 75 gallon tank, or any other tank for that matter. It's really all in the acclimation.

Running the lights 15" above the water surface is fine, you will loose a bot of intensity lower in your tank but that is fine.

[Dive_Master]

Scott,

The 250 Watts MH Lights are 15 inches above the surface, so that is 35 inches above the bottom of the tank.

The corals ( moon, and button coral) are all the way on the bottom and are still showing signs of severe bleaching.

I do not know what to do. I placed galss tops back on trying to cut down some of the intensity, I do not know if it is working, It should.

What should I do now.

1. Go back to PC lights
2. buy 175 watts MH bulbs
3. Raise the tank even more.

PLease help these guys are not doing too well.

[reefsus]

Some lps's can get used to it other can't. When i went from 4 4' vho's, to 2 250 watt halides on my 75. I did a nice 1 1/2 month acclimation. I came out with no loses except a fungia that was starting to bleach, he wont stop... So i was forced to get rid of him. I put him in my friends tank with pc, immediatly he stopped his bleaching and slowly started coloring up again

I also had a open brain, a couple candycane's, and favia, a cydarina, and all the euphyilla species and none of them were bothered. Except for when i upped my flow very greatly. Their still fine, just p***ed off, when my tunze is on.

[kevinpo]

Corals changing color and becoming very light or dark when lighting conditions change is not an indication of health of the coral. Bleaching of a coral is something that happens over the course of a day or two and then the coral dies quickly (usually from lack of proper acclimation time). The changing of a coral to a very light color (maybe even almost white) is a response to increased light intensity. They are trying to reflect more light back and corals that darken are trying to absorb more light energy. They will continue to live for years even in the pale condition. SPS corals will do the same thing. LPS will also withdraw much of their tissue trying to reduce the surface area (which reduces the amount of light energy they receive) and when put into low light conditions will expand greatly to increase it.
So it becomes a matter of what color you like your corals to appear. If you like them better in their previous condition then move them under a rock ledge or reduce the halide photo period time to about 4-6 hours. Increasing the height of the light fixture is also a good way to reduce the intensity. Every time you double the distance you reduce the intensity by 4 times. Conversely if you lower lights by half the distance you don't double the light intensity but increase it by 4 times (inverse square law).

HTH,
Kevin