Having a few rolls of E6 left that I didn't feel like spending $10/each to develop, and knowing that whatever was on them didn't mean much, I went ahead and developed two rolls of Velvia 50 and Elitechrome 160T in C41 chemistry.

They came out pretty well and I forgetting that this was E6 and not C41 (e.g. I should have done this one shot), I poured the used chemistry back into the bottles (dev and blix) and essentially contaminated the existing c41 chemistry.

The next day I developed a roll of Superia 800 (C41) in the same chemistry and all came out well.

Then, a few weeks later, I went to develop two rolls, both C41, and they were completely cleared.

It took me a few days of pondering before I figured it must have been the E6 film in the C41 chemistry that caused it to clear.

So the question is for someone technical: what happened chemically in this longer period of time to cause what appears to be a complete breakdown of the developer? I can only assume the blix cleared the roll completely because the developer wasn't acting at all.

Thanks in advance!