I just can't win the fight against the green "fruit-looking" flies.........after skimming the surface yesterday, I covered any gaps around my airlines & water-return with a towel, to try and determine how said flies were getting into my tank.  It's pretty clear to me now that they are reproducing on top of the water and on the surface of my glass top, and at a rate faster than I can battle.  Trapping them with apple cider vinegar isn't working at all, to date this method hasn't yielded even