Foamy marks in my negatives - advice needed!

My last two rolls of film have foam marks in the negatives. These are not from drying, but are from the development process.
Any ideas? I use Colortec Tetenal C41 in a patterson tank - Am I agitating something too much? I definately am putting in enough chemicals, but I am getting foam- you can see the result - interesting the first time it happened - maddening the second..
Would the issue be associated with the Dev, the blix, or the stablizer?
Any ideas?
Thanks in anticipation...
Mark

Note that the bubble circumferences don't show detail leading one to suspect developer. Indeed it does appear likely there is insufficient solution in the tank. Was the bottom portion of the image at the top of the tank? It looks very much like you have gotten, as you say, foam near the edge of your reel. Agitation could bring some froth to the top of tank but only if the tank is not filled properly. Did you pre-wet the film? Also, when you agitate do you use a correct tilt and twist motion? If you tilt the tank while twirling then you certainly should cover the film completely even if you are a little shy on the fluid volume. For Nikkor tanks and reels, I fill the tank with solution, replace the cap, and then tilt and twirl continuously for the first 20 seconds or so, and thereafter tilt and twirl three or four times every 30 seconds. With this technique a pre-wet isn't normally needed, at least in my experience it is not.

Thanks for the thoughts, mts. I just developed another roll - I added extra fluid (beyond what ws required and tried to minimize bubbles with a more gentle twist - This batch is looking fine.

If you are still getting foam, add one drop of Edwal LFN to the developer and it will prevent foam from forming.

Rick A said:

If you are still getting foam, add one drop of Edwal LFN to the developer and it will prevent foam from forming.

Click to expand...

I have never used Edwal LFN. Is it safe to use with any developer? Does it work with other solutions?

RPC

Its a wetting agent, but does work as I suggested, I use it all the time. I replenish my developers, and put one drop in every so often, when the stuff starts getting foamy. I use it for film and paper developers, plus it's my final rinse agent for drying.