In my opinion you don't even have half the lighting required for a BTA let alone a sebae anemone.
Generally speaking the BTA normally requires somewhere in the neiborhood of 4+ watts per gallon, and it can climb the rocks for better lighting.
The sebae is a difficult anemone to keep, even folks with good practical experience have difficulty in keeping them. So far from my research and others experience they truly seem to do better with metal halide lighting. A sebae will plant his foot in the substrate and therfore will be at the bottom of your tank furthest from the best lighting.
IMO you will need to at least double your lighting for the least light requiring anemones like BTA,RBTA or Haitian.
Thomas