I love water sprite. It's a good back corner plant, and awesome for sucking up excess nutrients and preventing algae growth.
In my boyfriend's tank, it used to grow like crazy, needing to be trimmed down every three or four days. (I would trim it down by pinching off one of the baby plants grown halfway up the stem and tossing out that baby plant.) One day, he got fed up by how big and bushy it was and took out most of the plant, only leaving in only a tiny little bush of water sprite. That was the day his algae problems started and the water sprite's had a hard time making a come back since then.