I am using Tetenal C-41 chemicals, which are re-used four times, and so far I've only been developing my slides in the last batch, after which the developer is finished. Now, however, I have brand new chemicals and some slide film that I need to cross-process, and I wonder if anyone knows if it will destroy my chemicals right away, or if I can develop more slide (or negative) film after the first batch? Will I need longer developing times? Will the colours go all crazy? Will it turn out just blank? Please help 
