c41 processing: bubbles in the sky

[morback]

Hello,

I hope someone can help me identify the culprit...

(picture edited so you can see the problem better)

Setup:
CPP2 + lift
Tetenal 5l kit
Portra 400 + Rolleiflex T
Agitation "P"
38C @ 3:15 (first batch in new chems)

I've had a few issues with the stabiliser in the past (leaving marks) but seem to have solved it. This though, baffles me. It doesn't appear on all the frames, just on some. I'm inclined to think it's the stab again (still).

1) what is it?
2a) can I fix it?
2b) if not, how do I prevent it?
3) would it show in print? (I can barely see it on this neg)

Looking forward to your insights!

 

[morback]

Tetenal has not answered my email since I posted this thread, but Jobo was kind enough to get back to me within 5mn:

The most common cause of this problem is insufficient amount of chemistry in the tank.
Depending on you CPP2 model, P might also be too slow a speed for film processing. You want to be around 75-80 RPM, and that can vary from machine to machine.

Lastly, it might also be foam buildup during the initial processing if you are using a pre wash, which i would recommend not doing as a start.

Things to try.