While you can get good coraline growth with NO lights, that 20w, as fishfreek said, isn't going to do much for you. The PC
system sounds great though...you'll love it.
It's normal not to see much on the rock at this point...most of my tanks were up for over a month before I started seeing anything at all. The pods
will probably appear overnight...you'll get up one morning and the glass will be covered with them.