Brian,(posted 8678 days ago)DO realize that the collapseable bottles have a big problem. They are not gas impermeable. The thin plastic required to fold, allows oxygen to diffuse through the bottle. So while you do gain with the lack of oxygen IN the bottle, you lose with the oxygen diffusing through the sides.
Glass works best. To handle the excess space, glass marbles work well, or Tetnal (Jobo) has a spray that displaces the air in the bottle to protect the developer.