Since I do not use c-41 except for in-house reproductions, I also use a non-professional system for developing c-41. This ar things I watch for. #1-Use distilled water with the developer, it is very sensitive to tap water issues if you have any. #2-I re-use the bleach and the fix pretty much equally. The good news is that you will be able to tell if the bleach is pooping out, in which case re-bleaching is Aokay. Just check the film before you put it into the fix. (you can use regular room light once you are through the pre-bleach). So I actually watch the process starting at this point as my choice for developing 4x5's is a translucent tupperware container. It is truly amazing, and since the bleach and fix can be more easily underdone than overdone; this helps guarantee by inspection that I let it work completely. #3-Also during the bleach step you need to shake the crud out of the container you are using. If it does not receive enough oxidation, it does not work properly or you have to nearly double the time. The other steps need gentle agitation as a rotary tube would offer.