how are your nitrates at 0ppm????
even with 2 x weekly water changes and a heavily planted tank a 0 reading would be hard to achieve unless you have a ery understocked tank. (someone here is bound to contradict this though)
and yes Flourish EXCEL works wonders on BBA, many threads here on how it works, I think most were resolved (hence the end of the discussion), best way imo is to squirt it directly on it with a syringe.
nice and simple page
http://www.aquaticcommunity.com/algae-control/removing-hair-algae.php