Agitation by water pump? Which pump?

[John51]

I'd like to experiment with using a water pump for film agitation. Empty the tank every x minutes...pause... pump it back in. Something for me to play with while figuring out the rest of the processor.

None of the processor posts mention what pump they use. Any ideas?

 

[revdoc]

I've thought about doing this for a paper processor, and in a prototype/proof of concept build I'd probably try a cheap 12v submrrsible pump off eBay. You can get them for a few bucks each, so it's no big deal if they fail.

 

[georgegrosu]

I used a Chinese aquarium pump - cheap.
It goes well but attention to the developer to not give air bubble.
Special photo pumps are expensive.
Aquarium pumps can be found at aquarium stores.
Aquarium pump are in the market, several firms that sell food for fish fry
have such pumps.
The Mr there was very cute and showed me in the basin
with water as flow gives more pumps.
So it was not complicated to decide.
It cost about 10 €.

https://abc-zoo.ro/15-pompa-de-apa-de-acvariu

George

 

[Nodda Duma]

Cheap aquarium pumps are the way to go

 

[John51]

Aquarium pumps are not reversible and it will need to be reversible.

 

[grahamp]

Peristaltic pumps are self-priming and reversible, but the flow rate might be too low. I suppose you could run 2-3 in parallel.

I can't see how you would empty and refill a standing tank fast enough for even development. Trying to feed developer in to the bottom of the tank while drawing it off at the top (recirculating) is going to be uneven.

 

[koraks]

I can't see how you would empty and refill a standing tank fast enough for even development.

Indeed. It's a recipe for some phenomenally irregular development. But who knows? It's an experiment, I understand. Not one I can see the sense of, but then again, I do some pretty insisible things myself from time to time.

 

[MattKing]

I can't see how you would empty and refill a standing tank fast enough for even development.

If the tank was was sufficiently large - say six times the volume of the reels - and the emptying and refilling happened at the same time, it might work.

 

[Nodda Duma]

Aquarium pumps are not reversible and it will need to be reversible.

Sorry, wasn't clear that I was thinking a pair of pumps. Two cheap aquarium pumps, one for each direction, are still cheaper than other options

 

[John51]

Two cheap pumps would get me started.

I timed the flask filling and emptying in this thread:

https://www.photrio.com/forum/threa...fp-yet-another-desktop-film-processor.164871/

Including some rinses at the very bottom of the flask, it took 40 seconds for 500ml. (10 secs on video 4X.) That's an effective rate of 45 litres per hour.

All hands off table top processors are going to need a pump. One I saw a few years ago bubbled air for agitation. The open source project in the link uses the Rondix method. (Very good if you want to process another film as soon as it has finished, no reel to dry.)

I'm wondering if pumping alone can do the agitation. If so, makes for an easier build. Only one way to find out.

 

[Nodda Duma]

It should, especially if you angle the outlet to circulate the water. My darkroom doesn’t have running water, so I use an aquarium pump to circulate water in my rinse tray. Works like a charm...esp. considering the pump is like $6

 

[georgegrosu]

I apologize for not correctly understanding the notion of processor.
For me, it's something like a film developers, mini-lab.
The manual development dose I'm not using for notion of the film processor.
A pump to operate on a developing machine must be placed below the solution level (to be primed) and have a uniform solution distribution system in the cuvette.
A pump that pulls out the solution and puts it in one place will never have a uniform agitation for film.
Processing KODAK Motion Picture Films, Module 2Equipment and Procedures page 2-14
https://www.kodak.com/uploadedfiles...t_en_motion_support_processing_h242_h2402.pdf

George