ya black florite and i love that stuff i also have the black sand in my 5.5 gallon and i love that too.
i would have never used the UV but i had a huge green water problem and did everthing i could think of and it never went away so i tried the uv and im not one hundred percent sure if it helped or not. but the green water is gone now so i think im going to try removing it and see what happens.