That ballast looks like it will work just fine. I just have to ask and please don't take this the wrong way I mean no disrespect. Your friend the electrician, he would know the answer 100%. It must deal with t5, t8 etc etc etc all the time.
But in any event. That ballast appears to be sufficient enough.
"When creating an aqua scape, strive for the beauty of imperfection, as its art and there is no wrong or right, it's left open for interpretation" James Findley