There is probably an "I told you so..." somewhere in all this, so I am bracing myself. I have been using R09 to develop my Arista.EDU 100 ASA 120 film for the past few months now with no problems. I just finished my first bottle that I purchased from Freestyle and I usually develop 2 rolls at a time. I finished shooting a roll this morning and just attempted to develop this roll plus another I shot last week. When I took out the bottle of R09 concentrate, a dark precipitate had formed in the bottom of the bottle. I had noticed this preciptate forming the last time I used it. I looked up the threads here on APUG that talked making a Rodinal-like developer and they all commented that a precipitate would form when you mixed it and that all the precipitate would not disolve. I figured that as the R09 concentrate bottle got emptier and, this being TX where our normal inside temperature is above 80, the vapor pressure change was causing some preciptate to form. I mixed and developed as usual and there were no problems. Negatives looked great. So this time, the amount of precipitate was greater, I warmed the bottle in running water, shook it vigorously, and most but not all of the precipitate disolved back into solution. I mixed the developer and proceeded to develop. Both rolls came out absolutely blank - - completely... not a shadow or hint of anything on the film... as if I had developed 2 completely unexposed rolls (which I have done by mistake in my almost 50 years of doing this) ...so completely blank that I checked the camera and back to make sure it is working (...it is). So this being the first bottle of R09, my questions are something like: Obviously, whatever preciptated out was an active ingredient that was not the same once I warmed it and shook it back into solution. What should I have done? Toss the bottle and opened a new one? Any thoughts? Thanks.