Acan dying??

[albaby]

I have used the boards since I started almost 4 years ago but this is my 1st post. Maybe not the best pic but you can see in the lower right my problem.

I have 11 acans on the sand in my 50g tank under a 250W 14k Hamilton bulb and a recent addition looks to be dying off, I just noticed since all the Acan Lords were close together. The other acans are expanding with tentacles extended even 2 that I moved from my 24g JBJ since they seemed to bleach out under 65w pc's or maybe my cleaner shrimp picked too much stealing food.
Here are my parameters.
temp, 78
nitrates, between 5-10
ammonia 0
nitrites 0
Phosphates 0
Iodine 0.04
calcium 400
dKh between 8-9
Magnesium 1100 which I know is low(I used a Red Sea test kit) I tested fresh mixed salt (Reef Crystals) and it tested 1100. Based on this # I added Tech M to rasie
ph 8.3
I dipped the coral in a Revive solution this morning and plan to do a 10g water change.
Any suggestions before a goner?
Thanks

 

[kraylen]

Too much light I assume.

 

[luvmyreef]

Too much light? Would it start at the bottom?

Maybe...But what about chemical warfare? What this coral touching another? Or is it in close proximity to another? Be aware that Acans are nocturnal predators and digest organisms within reach, so be careful with placement and distance between colonies.

 

[albaby]

Thanks all for the info. I have the acans on the sand and the halides are 10" off the glass. I will try and move it to a shaded area and see what happens. All the other acans appear to being thriving under the same light but I will admit that the colonies are close together so some nighttime activities could be a cause.

 

[1boatnut]

With 10 other Acans all in the same proximity to each other,I'm not convinced too much light caused this issue.
I also doubt this issue has anything to do with your current parameters,considering again the other 10 are all ok.
luvmyreef may be on to something,or has something possibly picked at it starting recession? (my guess)
I hope whatever issue caused this,the remaining heads on the Acan in question stay healthy.