I could never keep xenia in my tanks (friend also had issues). I used oceanic salt, which I've read is low in iodine, as well as reading xenia needs some in the water.
So, I changed nothing except dosing Seachem Iodide, just a little in any new water I mix up for water changes, and then once or twice in between changes if needed. Xenia is now doing great. Shrimp haven't had molting problems either since.
Not a perfect scientific trial, but it's given me positive results so far.Either way, you should be careful with how much you dose.