HMM. the xenia heads falling off...im pretty sure that that means the xenia is under lots of stress with something in the water. Most of the time, it is alk and iodine. These tend to really affect the xenia, esspesially the iodine. Iodine does seem to do something that the xenia doesnt like, most of the time it will die if the iodine levels are too high, and will also die if the alk is too low. Alot of people say that xenias like hardly any current, while others say high current. High current make it harder to pulse, and no current tends to make them "droop" some of the time. I have found it that medium current works great with most xenias. Xenias tend to all have different needs. Xenias like medium lighting, and medium current, and SOME nitrate. Nitrate just gives them something that they like, Around 5ppm is the best for xenias, any higher and they will not live as good/die in the tank. What are your levels(nitrate, nitrite, ammonia, alk, pH, iodine, and calcium?) What lighting do you have? How much current and light do you give it?
PS, welcome to the BB!