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Thread: Some JOBO CPA questions

  1. #1

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    Some JOBO CPA questions

    Just acquired a JOBO CPA2 and have some questions.

    1. Since my darkroom's ambient temperature is a constant 68 degrees from June till the end of September (I am very lucky) I don't really need to use the water bath. I assume that I can run the JOBO without water in it as long as I don't turn the pump on (intern activation of the temp control).

    2. On the other hand, I can easily keep the water bath filled. But how long till I might have problems with whatever type/kind of growth in its 68 degree water? Or is this something I should just not worry about and maybe change the water every month? Would adding a drop or so of bleach or chlorine prevent any type of growth in the water? BUT would that drop or so of bleach or chlorine harm the JOBO in any way?

    3. Can (any) 120 stainless steel reels (I think mine are Kinderman brand) be used in any of the JOBO tanks to process 120 film? From my JOBO literature it seems that for processing 3 rolls of 120 film I would be using 1520 and 1530 tanks together. The JOBO literature mentions using a "special center core" with their JOBO stainless steel reels. What is this "special center core''?

    4. Last off... Can anyone recommend a good digital readout thermometer to use with the JOBO?

    thanks in advance

  2. #2

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    Re: Some JOBO CPA questions

    1. I'm not sure if it would be alright for the jobo or not. I always use water as its my standard practice and changing the process in my experience leads to dumb errors when I forget that I changed something.

    2. I have kept water in the tank (A CPP2) for a week or so without issue. However I think it may be down to what your water supply is like. I now drain the jobo everytime unless I'm going to be processing within a few days.

    3. No idea about the steel reels. I've only used the plastic reels and a collection of tanks. Currently using a 3010 for my 4x5 developing.

    4. I use the following for my process thermometer. (Probably overkill but whatever) I read that its better to be consistent then perfectly accurate.
    Thermoworks.com Therma K Meter & Probe Kit, with Fast Response 313-158 Probe and NIST-Traceable calibration certificate.

    I'll check process temps at the water outlet of the jobo, (As instructed in the CPP2 manual) and also the chemistry in the bottles. (Cleaning after each check).

    Hope that helps at least a little bit.

  3. #3
    Drew Wiley
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    Re: Some JOBO CPA questions

    I use a Jobo tempering bath for keeping my own color chemical bottles at correct temp. My own roller machine is separate, and much more seriously built than a Jobo. I change the water daily. These are not water heaters, and you need to start with water reasonably close to the actual temp you need the built-in immersion heater to maintain. If you do decide to leave the water in, a little cupful of thymol-based Listerine mouthwash will keep water mold and algae at bay.

    I've never cared for digital thermometers. I have a couple of them, but they read too slow for me, and need periodic recalibration anyway. I'll stick with my trustworthy Kodak Process Thermometer.

  4. #4

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    Re: Some JOBO CPA questions

    The water in the Jobo base slightly floats the drum easing the load on the motor, as well as helping to maintain a constant temperature.

  5. #5

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    Re: Some JOBO CPA questions

    1: As long as the heating element is guaranteed not to turn on, you could use your Jobo without any water. My CPE2 (different product!) allows the thermostat to be set so low that the heater stays off all the time. If you can nudge your CPA in a similar fashion, then yes, you can run it dry. I would advise against running it that way unattended so in case the heater does for some reason come on you can turn everything off and prevent any damage.

    2: Algae growth will be a reality within a few days up to a few weeks depending on light levels, and bacterial growth will also emerge. Chlorine/bleach will dissipate out of the water within a few hours so you would have to repeat that treatment on a daily basis. Even so, I think you'll be left with slime and crud within a few weeks. Sorry, no good news in this department at least based on my experience. Be prepared to replace the water every few days with a thorough cleaning in-between. I don't think it's worth the hassle really; I just fill it just before use, then drain just after it and give it a quick wipe. Some of the crud that's on it from the days when I left it filled will never come off.

    3: I can't comment on if the Kindermann reels will fit, but the center core of the Jobo tanks is CRUCIAL as it's part of the light trap. Do not think of using your daylight tanks as intended without this center core; you WILL have horrible light leaks.

    4: I just use a generic digital meat/steak thermometer. It's good enough for my purposes (mostly C41 development). Being a vegetarian, I have no other use for it anyway

  6. #6

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    Re: Some JOBO CPA questions

    1- I've never run my CPP-2 so no idea if it would cause any issues; other than, perhaps, an increased strain on the motor as mentioned above.

    2- Algae will definitely grow, but the rate of growth will depend on your environmental factors. I fill mine, use it, then dump each time.

    3- Never used stainless steel reels in my Jobo, but I know this type of reel requires a special center core made by Jobo. Don't know if the Kindermann reels would fit this core.

    4- I use a cheap electronic stopwatch to time all steps.

  7. #7
    Martin Aislabie's Avatar
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    Re: Some JOBO CPA questions

    1) I always run my CPP with a water bath - what ever the ambient temperature - and I only ever process B&W at 20C/68F.

    2) I fill, dump and dry out the water bath every day - even if I am planning to use it the next day.

    3) I'm pretty sure my CPP instructions say something about never using chlorine bleach in the water bath.

    4) I've never tried to use anything but Jobo tanks and reels - and 100% agree about the need for the centre core - it is a vital part of the light trap.

    5) I use a fairly ordinary digital thermometer - but I have calibrated it against my own "master" alcohol/glass thermometer.

    6) I use a Paterson 3 step process timer (Paterson Triple Timer) to time the whole dev/stop/fix process.

    Martin

  8. #8

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    Re: Some JOBO CPA questions

    From the original poster...

    1. If having water in the JOBO base slightly floats the drum easing the load on the motor per Jim Noel... seems like a no brainer to go that route.

    2. Don't need to deal with algae growth. Looks like I'll be filling the JOBO with 68 degree water before using it and draining it there after.

    3. from Koraks "the center core of the Jobo tanks is CRUCIAL as it's part of the light trap." Well after researching it, that center core definitely looks too large in diameter to put my Kindermann reels on. Evidently JOBO offered SS reels ("NEW FROM JOBO" page insert in my 1990 JOBO catalogue) that did fit on their center core, but I have never seen those JOBO SS reels up for sale.

    4. Remembered that I had a Kodak Color (glass & mercury) thermometer on the shelf. With a round shim it fits great inside of the JOBO's thermometer clip. Fortunately my Kodak color thermometer matches the readings on my 2 Kodak process thermometers. That Therma K Meter with the Fast Response probe that Deyoung mentioned is definitely on my to-buy list.

    thanks...

  9. #9
    Drew Saunders drew.saunders's Avatar
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    Re: Some JOBO CPA questions

    Quote Originally Posted by Greg View Post
    From the original poster...

    3. from Koraks "the center core of the Jobo tanks is CRUCIAL as it's part of the light trap." Well after researching it, that center core definitely looks too large in diameter to put my Kindermann reels on. Evidently JOBO offered SS reels ("NEW FROM JOBO" page insert in my 1990 JOBO catalogue) that did fit on their center core, but I have never seen those JOBO SS reels up for sale.
    I have the stainless steel 120 reel for my 1500 series tanks, and somehow my Monday Afternoon brain remembered that they're currently made by Hewes. Not cheap, try to find some used ones, as they're pretty sturdy.
    https://www.freestylephoto.biz/15001...Paterson-Tanks
    https://www.flickr.com/photos/drew_saunders/

  10. #10

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    Re: Some JOBO CPA questions

    Quote Originally Posted by drew.saunders View Post
    I have the stainless steel 120 reel for my 1500 series tanks, and somehow my Monday Afternoon brain remembered that they're currently made by Hewes. Not cheap, try to find some used ones, as they're pretty sturdy.
    https://www.freestylephoto.biz/15001...Paterson-Tanks
    $79.99 each!!! I just purchased three NOS Kinderman 120 reels for about that same price. I'm starting to shoot more and more 120 film lately, so may be something to think about in the future. Four of those reels plus a 1500 series tank and center core is definitely not a minor purchase, but selling one of my LF lenses that I rarely use to acquire 4 Hewes SS 120 reels and a 1500 series tank & center core is weighing on my mind.
    Thanks for the Info...

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