I'm currently learning Pt/Pd. I've gotten better and better over the past few weeks with lots of reading and practice. Last night, however, I ran into a problem. On every print I made, I got what looks like small rust spots. They are about the size of a pin head and are rust colored. I read something about "plauge spots" but I think this is different. Could this be gunky developer? It does have some sediment in the bottom. I know you can re-use oxalate developer, but can you re-use ammonium citrate?