I've got the Aerogarden Classic supplemented with a 100W Daylight CFL at 5500K, and I've got 7 seedlings growing. In just about 4 days, they've made incredible progress. Two of them are over two inches, 3 are about 1.5 inches, one is just sprouting, and the other is still releasing the taproot. The five tallest are all showing their water leaves, which are dark green, ridged and healthy. I've got it on the tomato setting which seems to work well, and yesterday, I added an airstone.
After reading more threads, I think I might have too many plants growing for such a small reservoir. On the other hand, you've got to figure some males will arise that will have to be removed later on, so you might want to overshoot the mark a little bit. Which model are you using?