Planted Tank Guru
Join Date: Sep 2004
Location: Garden City, KS
I think your choice of livestock is fine, as long as you don't overdo it with the shrimp. As far as the light is concerned, the most common fixtures that people (myself included) use on a 20L are the Coralife Freshwater Aqualight 30" 2x18w fixtures. I have 2 of these fixtures, for 72w, which gives me medium-high lighting. But many people successfully use a single one of these fixtures, provided their choice of plants doesn't require high lighting.
Go to bigalsonline.com and do a search for coralife 30" and you'll see it. They are nicely priced, too.
Best of luck!