I have the biofilm disappearing by itself if I don't feed the fish for a couple of days... Feed less and often than once in bulk.
sadly that does not always work. i have a tank that i feed once or twice a week and i still have have biofilm, the amount of food that i feed is minimal because the fish is rarely out for food. of my 5 tanks 3 have biofilm, really its only of 4 tanks because one has a surface skimmer.
the best "cure" to biofilm is surface agitation, or a surface skimmer.