Coral Dying??

I bought this yellow star coral about a month ago, it was doing really well until I put in some Xenia, then it started to shrivel up and hasnt been out much in the last few days. The only other thing is most of my turbo snails have disappeared (Or become doorways to my pistol shrimps cave). The Xenia shriveled for about 2 days and is now fine, but the star coral hasn't.
I have checked my water, the Nitrate is up to about 8ppm the ammonia is 0, and the Nitrite is 0, have done 2 20% water changes in the last week, and have cut down feeding in the tank.
The tank has around 10 hermits,8 snails (that are laying eggs every few days) a cleaner shrimp, a Pistol shrimp, an orange shoulder tang, tailspot blennie, sunspot gobie, and a mandarin. It contains living rock thats full of life, copiopods are rife. I treat it wit purple up every few days, and feed the corals on zooplankton. There is also loads of culurpra that I have to weed every few weeks as its growing fast.
I have put some pics below and would appreciate any help, as I dont know whats up..
Thanks
Warren.

 

maybe its too hot

 

I would stop with the zooplankton, and try phytoplankton, It does not appear that you have anything that feeds on zoo. I assume the rest of your parameters are OK, pH, sg etc.

 

I would cut out the purple up as well, it can make your PH swing pretty hard and that could be affecting your corals.

~Will.

 

Thanks for all the help. The water is around 80-82, SG 1.025-1.026 PH - 8.4, Ammonia 0, Nitrite 0, Nitrate 8-10. Copper 0
All my turbo snails seemed to die off a few weeks back, but the normal snails, hermits, cleaner shrimp, Pistol shrimp & Living rock have been fine.
I think it may have been the hermits or the pistol shrimp (The shrimp keeps using them to plug his cave)
The LFS that I got the coral from about a month ago SG was 1.021 which i though was way to low for a reef.
I have also weeded out 2/3 of the Culurpra today, and moved the coral about 1ft away from the xenia.
Anyone have any other Ideas?

 

first off how big is your tank and when did you start it

 

sounds like if your clean up crew is do\ing good and lalying eggs there is plenty of alge and or bacteria ck water temp salinity kh substaine coral and or soft corl life and fish not snails?

 

Been setup for about 4 months now, 200l. Fish are Orange Shoulder Tang (Juvenile) Suntail Goby, Brown Spot Bleny, and a Mandarin. The mandarin is eating frozen & dried food as well as the copiopods that are abundant in the tank. Also add pods. also cleaner shrimp & Pistol shrimp doing great.
I have weeded out 2/3rds of the caulepra and added polyfilter to the filter system and protien skimmer. And added a fluidized sand filter. Still dont know whats up with it though. Whats the best reef temp (im 80-82) and sg is around 1.025

 

I keep my water temp between 78-80. Sounds like it might just be the cleaner shrimp. Mine upsets some of my zoas on a regular basis.