I can't keep Xenia and Polyps

[iechy]

Here's a tough one I can't crack. Everything I put in my tank thrives except for Xenia, which I know can be touchy, and almost any kind of polyps other than star polyps. I have tried a few different buttons, yellow polyps etc. and they always die off slowly. Can anyone think of any water condition whose state might be problematic for these two corals but not others? I have all types of LPS and softy in the tank with great success eveything grows and is happy. BTW, I don't think it is a case of something munching on them because of the way they seem to go.

 

[reefnut]

Try checking your iodine levels. Usually water changes will more than replenish your iodine but depending on your water change schedule and type of salt it may be depleted.

 

[iechy]

I wonder, though, are the polyps in question succeptible to iodine deficiencies too? I tried the iodone route in the past and that didn't seem to be the problem. My alk is on the low end though so maybe I'll work on that. I just hate changing anything though since everything else is happy. On the plus side, everything that is happy may even get happier if something improves. Thanks!