I have an apron developing tank for medium format and I get air bubbles on the upper side, 1 cm wide, for the entire length of the film. I've agitated it quite hard with clockwise-counterclockwise moves for about 15 seconds before closing the tank and another 15 seconds afterwards, yet the bubbles are still there, although I'd hoped all air inclusions would rise to the surface of the developer after all that agitation. I have two aprons, one made from clear plastic and one from white opaque plastic. Both seem to have similar dents. How can i distinguish between agitation aprons and turning aprons? (my tank - TRIPLEX - is an agitation tank) I used the white apron for my first two rolls developed in this tank. It has a plastic clip used to fix the rolled apron to the reel. Both films got stuck to the apron on the lower side for most of their length. Someone told me it was due to the clip that was keeping the apron from freely move inside the tank during developing so i'd tried the clear plastic apron that lacks the clip. Indeed, no more film sticking to it but instead the air inclusions appeared. I'm really confused... Am I missing something? Thank you!