I've had xenia for over 2 years, started with a couple of small stalks, and now its taken over my tank. I have to disagree with having perfect water quality. For awhile, I wasn't on top of my tank maintenance and water changes and it grew even bigger. I don't understand it, but I have given it to friends and none of them have been able to keep it alive. One thing I know though is, they need to be supplemented with iodine, they love it. I would say some of my stalks are easily over 5-6 inches long.