I have a 20g Long as well. Very nice tank. Only a few of us out here. As for lighting I am running a CustomSeaLife (Orbit) 2x65w PowerCompact fixture. I have two Crocea clams, Sun Coral, Hammer Coral, Kenya Trees, and various Zoanthids doing well in this tank. I dose B-Ionic and DT's. I also spot feed Cyclopeeze.
HTH