Some years ago in our San Francisco museum, the flourescent lights were installed with some sleeves said to reduce UV. I don't know what brand they were, but they quickly cracked and crumbled right off of the lamps. No good. Instead of replacing them, we laid sheets of UV filtering Mylar over the "eggcrate" louvers that were beneath the light fixtures. The material is 5 mil Mylar laminated with the UV filtering material the photo labs put on prints. We cut pieces of it to protect individual documents on display (in addition to the UV filtering plexiglass case covers. The Heard Museum in Phoenix has their lights in boxes above the exhibits. The light goes through transluscent UV filtering panels. Essentially, sleeving tubes does not seem to be the answer. Design the exhibit cases and display areas to have a separation between light fixtures and the exhibits and visitors.