most UV sterilizers are built to work for ponds/ freshwater, or marine. the difference between the two is the distance between the bulb and where the water passes, and for marine tanks they're most effective at a certain size, what im not sure. people have different oppinions on UV, they do help to get rid of parasites, but also stop the growth of good algae etc. if your UV is the right size, and you clean it out good i suppose you could use it.
-Justin