Depending on the amount of care you want to give it, you could light it with anywhere from 20 - 50 watts/CF. Anything over 20 watts in your tank will need good balanced fertilization and a carbon source of some type to push them.
2.5 to 4.0 wpg is not considered super high light in a tiny tank such as yours. The wpg rules fly out the window with small tanks, and I find them much easier to correct and balance that larger tanks.....just my experience, and may not be true for everyone.
As mentioned above, I also find the EI method the best way to feed tanks with a decent amount of light over them. I also agree that over fertilizing is a waste of time, effort and money. Just give them what they need to balance the fish load, light and plant mass.
Len