Here are some excerpts from an article by Robert Toonen entitled Aquarium Invertabrates. Google for th efull article, Interesting reading. The following is only a taste please go read the entire article. Tube anemones are not anemones by the way.
Tube anemones can be an interesting and very attractive addition to a reef tank if the proper conditions exist. However, that last part 'if proper conditions exist' is critical, and more often than not, the conditions preferred by tube anemones are not those maintained in our home aquaria.
These animals live with their tubes buried deeply in fine sands and muds. If you have a bare-bottom tank, or one with either a thin bed or coarse (rice-grain size or greater) gravel, these animals will not be able to find a spot that suits them and will most likely perish in short order in your aquarium. In the wild, the burrows of large animals can extend a couple of meters, so a sandbed that is only a couple of inches deep is just not going to cut it for these animals. In cases where I am worried about the depth of the sandbed for a tube anemone, I make an artificial burrow for them. Simply cut a section of PVC pipe into which you can stick the animal's tube and fill the pipe around the tube with sand.
Finally, because they are nocturnal, they are obviously not photosynthetic, so they do not care about the lighting in your tank. Given that, they will also prefer an area that is shaded from direct light and they do not tend to thrive in areas of intense flow.
