Big tank = Foamy Developer?

Hi Everyone.
I've been noticing of late that when I use a 1000ml tank to develop two rolls my developer (usually Rodinal but some occasional HC-110) sometimes gets foamy. I notice this when I uncap the lid and pour out the developer. However I don't seem to have this when I use a 500ml tank for a single roll. I did a search on this and it appears the general consensus is Photo-Flo residue on the reels. I do soak my film in Photo-Flo on the metal reels but I've always use the hottest water my faucet will dispense to rinse the reel along with a quick scrubbing with a dish washing bristle brush I use for this propose only. I just checked my reels right now and they feel fine, not sticky at all. So do you think that maybe the extra air space in the 1000ml tank is causing the foamy bubbles because of the increased turbulence during agitation? I agitate four gentle inversions for ten seconds at the start of every minute. Maybe the 500ml tank with less air space is a better choice? I don't know if this is causing any uneven development or not. I shoot an awful lot so I like the idea of developing two rolls at a time but if the the 500ml tank for one roll is a safer bet then that's what I'll do. Any ideas? Thanks.

I have different sizes of Paterson tanks and I use the smallest tank suitable for the number of rolls I want to process just because smaller tanks are easier to handle. I have noticed frothy developer from time to time but I am not convinced it has anything to do with tank size and to my knowledge it has not affected development in any way that I can see. I use developer one-shot so it is never re-used. If you notice foam/froth be sure to tap the tank firmly on the counter after agitation. This will reduce the chance of air bubbles in the reels. If you do get air bubbles this will show as a light spot (underdevelopment) on the film. It will of course print as a dark spot. You can load 2 x 120 films on one Paterson reel (they are designed to take 220 which is twice as long as 120). This saves chemicals and I often use this method. I am assuming you are processing 120 from the volume of developer you mention.

Are you using extra empty reels as spacers, the reels chugging back and forth could be causing all that foamy badness. If the film looks good I wouldn't worry.

Svenedin said:

I have different sizes of Paterson tanks and I use the smallest tank suitable for the number of rolls I want to process just because smaller tanks are easier to handle. I have noticed frothy developer from time to time but I am not convinced it has anything to do with tank size and to my knowledge it has not affected development in any way that I can see. I use developer one-shot so it is never re-used. If you notice foam/froth be sure to tap the tank firmly on the counter after agitation. This will reduce the chance of air bubbles in the reels. If you do get air bubbles this will show as a light spot (underdevelopment) on the film. It will of course print as a dark spot. You can load 2 x 120 films on one Paterson reel (they are designed to take 220 which is twice as long as 120). This saves chemicals and I often use this method. I am assuming you are processing 120 from the volume of developer you mention.

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Thanks Svenedin. I do tap the tank after every agitation cycle. I would rather use the 500 ml tank for two reels of 135 film, but with Rodinal 1+50 the tank will not hold all the liquid so I have to use the bigger tank. Why don't they make a tank in between these sizes, like a 700 or a 750 ml tank?

darkroommike said:

Are you using extra empty reels as spacers, the reels chugging back and forth could be causing all that foamy badness. If the film looks good I wouldn't worry.

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Yes, I do have empty reels in place and I have those secured with a piece of plastic that prevents all the reels from moving back and fourth during agitation.

No idea, I don't use Rodinal. Funny, I don't use developers from the 1890's with films from at least a hundred years forward.

I'm not sure the foam matters, if the film spends most of the time fully submerged.