zoos are slowly closing

ive had my tank up for nearly a year now and i have 2 types of zoos in it the problem is that one colony of zoos is slowly dieing off. the polyps are slowly no longer opening it started as one then three then five so on and so on. has anyone ever had that experience. all input is appriciated.

thanks,
LOKI

 

Have you added anything new to the tank? have you checked your water quality?

 

It may be that you are experiencing a reaction to chemical/toxic warfare from another coral in your tank.
Either that or you have a problem with your a)water quality, b)bulb inensity possibly!

 

In my expierience zoos seem sensitive to high salinity- do you have a refractometer?

 

There could be any number of reasons. However, I would take a look at this thread.

http://www.3reef.com/forums/general-reef-topics/any-ideas-what-37954.html#post347535

 

yea i just checked my water quality and the numbers are right on the money but the salinity is a little bit high ....ill do a water change and see if i can lower the salinity a little bit.....but on another note i was told my my lfs that corals generally like water with a higher salinity, any truth in this???
LOKI

 

Depends on the coral- some of my Lps seemed to like it higher but my Montipora's didn't seem to care for it at all

 

I run mine above 35ppt and this is the case on a natural reef where salinity is 1.026 and higher. If only one type of zoa are dieing off than it might be their placement in the tank, maybe too high a flow, but you said you have had them for some time. Have you moved water flow devices? Could also be Zoa nudis consuming them, though I have no experiance with this myself, but have read about them. I don't know if they are easily seen or not. You don't see any flatworms do you? What type of fish do you have and inverts (crabs, etc)? Might check Reef Central magazine articles and do a search and maybe ZoaID.com, maybe some info there.
Might be best to set-up a small quarintine tank and make new water, mod lighting and observe the polyps to see if you can spot anything on them.

 

One more thing. Where are your zoas placement? Are they near the bottom. I was under the impression that certain gobies do lots of sand sifting and possibly sand is being dumped on them? Or one of the gobies is sitting on them? And you stated that they are not opening. This doesn't mean they are dying. Are they waisting away? If all else fails, try moving them to a higher location or where ever.
I looked at the pic of your tank, so now I ask, do you have enough flow over them?

 

no there is no visible parasite on them and no change in water flow...the wierd thing is one part of the colony is still spreading but the other side of the colony is dieing off????? very wierd