Steve,
I have an interesting story to share with you. Sad, but perhaps helpful. All of my Xenia have now died - every one of them (and I had a nice collection started). The other day I was up late and realized I had not dosed in awhile due to changing over to my new tank. I typically use Kent liquid supplements and have the ingredients to make about a 5 gallon container of top off that I lace with the supplements and it keeps things running smooth. I include things like Iodine, Magnesium, Strontium, Reef Builder, Calcium and trace. Well becuase my RO unit takes too long to fill up the 5 gallon bucket and I was tired, I said what the hell and dosed the supplements directly.
Mind you I have not dosed in awhile so my naive and sleep deprived mind thought I should 'make up for it.' by adding a little extra to get the params back in order. Well a day later, all my xenia curled up and soon died. I am almost certain it was the Reef Builder (alkalinity) because I really laid it on. All of my other corals are doing great, but xenias are particularly sensitive to alk changes and of course paid for my foolishness. So although your Alk may be good on a test, what it does not tell you is how fast it got there. The rate of change is what did me in.
I also hear it works the same for Iodine with Xenia particularly, but for me it was the Alk.
Hope this helps!
A lesson hard learned
