I usually use the 2830 tank and process two 8x10s at a time although I have a 1520+30 tank that handles a single sheet and uses half the chemistry of the 2830. I keep the unmixed concentrates in the original bottles. My experience has been that the bleach-fix concentrate will go bad before the developer concentrate. When the mixed bleach-fix looks puny (thats a technical term for looking pale and weak) I know that it is on its last leg and that I should get some fresh bleach-fix. Right now I am using concentrates that I got in Feb 2010 and they are working fine.
Originally Posted by dslater