I have some questions regarding at home Spiral Tank processing. I have been mixing 2 litres of chemistry for 100' rolls of color reversal(ORWO/Svema & Kodak E-6) and, just recently, color negative(ECN-2) 16mm film. After running the first devloper, the solution is sometimes black and seems to effect the image of the bottom 50' layer of film (dark and muddy). Should I only run 50' at a time at the top spiral? Should agitation be constant to mix chemistry, or maybe try to filter the developer before running the other 50'? You advice would be greatly appreciated.