While working with a newly established planting, the plants often won't grow well until they can get their roots established in the substrate. It is best to start off with a short lighting period of maybe 6 hours and work your way up to longer light periods. I run 8 to 10 hours of light over most of my planted tanks but it is not a great idea to start that way.
An electronic ballast is one that uses electronic circuits, instead of a transformer, to provide the right voltage to your fluorescent lamps. They average much more energy efficient than the older style ballasts.