OK, this is weird. I added a Koralia Nano and 2 Koralia 2's last week and the next day and ever since my Xenia has been acting similarly. I would describe its behavior as the same as yours. Still pulsing, doesn't stay all sucked into itself, but it's definitely smaller. Will follow this thread... EDIT: I mean I added 2 Koralia 1's, not 2's.