Lighting in a 20H


Hi All,
I will be setting up my 20gal (24" x 12" x 17") soon and want some opinions on lighting options. Right now it just has the standard flourescent 15w hood. For now, I won't be getting any corals or anything, so I will probably just use the hood that I have. However, I want to eventually be able to have corals and need to know what kind of AFFORDABLE lighting to get. I've read so much about lighting lately and still feel so confused. Any opinions would be VERY much appreciated!
Thanks :joy: