Sorry if this has been asked before, but I didn't see a similar topic posted recently. Anyhow, I've had some trouble getting all of my frames evenly developed. I'm using an older Patterson Tank (4) for developing some black and white film. I have been using 10seconds of inversion every minute with Arista film and T-Max developer. Some frames come out very nicely, but others are too dark and some come out completely black. I am fairly sure this is not a problem with the camera exposure, since it has occurred with two different cameras. Speculation on the problem: Are the Patterson reels too small for 36 exposures? It seems to fit pretty well, but could the film be overlapping? Not inverting enough? But would this affect the frames that have been coming out well? Thanks for any help. Please understand that I am fairly new at developing.