Greetings! Jobo owners, do you use the trough to heat the chemistry?

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PC Chen

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The highest possible water level only covers about 2/3 of the 1L bottles, less than half about the graduates. So that even when room temperature is around 30 degrees and CPP3 set to 38.0, the chemistry is just around 35~36; Still far from the C41 standard.

_DSC3975.jpg

After two attempts on September I gave up and have another stand alone thermal static tank as the main chemical heater. The thermal tank serves much better, but that's additional cost add up to the already premium priced CPP3.

_DSF1891.jpg

How do you use your Jobo trough?


happy new year,




PC
 

Jerry Thirsty

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I adjust the temperature setting based on an accurate thermometer in the bottles, not what the display is telling me.
 

BMbikerider

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As Jerry Thirsty says always use a reliable, accurate thermometer to check the temperature of the measures. Always check inside the measures, not that of the heating water bath which can be 2-3 degrees warmer. I find for B&W I have to set the JOBO heater to approx 22c and for the C41 set it around 40c to get the baths up to the right temp. I tried it once as an experiment, setting the JOBO dial at 38c and leaving it overnight and in the morning the liquid in the measure after 8 hours was still only 36.3 degrees.
 

Ed Bray

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The level of the bath has to be increased once the pump is running to get good coverage of the chemical bottles and graduates when using the trough, you just have to either add a short hose to the overflow outlet at the back of the processor or drain some water off when you turn off the pump as the water level will rise in the trough and may well come out of the overflow and go over the working surface or floor if not sat in a bath or container.

As I have mounted my CPP2 on a trolley to move it out of the way when I am not using it I have to be careful about the tank levels.
 

Tom Taylor

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In my CPA-2 I maintain the water level just slightly below the cap so that the chemistry is completely submerged. I always fill the unit with water that is about 5 degrees from the processing temperature and let it warm up and then mix the chemistry and insert. The temperature is monitored at the troughs outlet which gives an accurate reading of the temperature of the trough water. Its easy to maintain a constant temperature during processing by carefully monitoring the thermometer and making minor adjustments but the temperature is always constant throughout the developer cycle and usually remains so until the later steps when it may drift 1/4 degree but at that point its meaningless.

Thomas
 
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PC Chen

PC Chen

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I have a CPP2. It warms the bottles quite nicely, though it takes about an hour for them to come to temp and sometimes I cheat by nuking them lightly first, up to about 33C.

Hello polyglot,
I haven't had a chance to thank you personally. Your film FAQ really save me a lot of time from collecting info here and there.
It's one the best practical reference I can find to complement official manuals by Kodak and Fuji.

The Jobo heater really is not that efficient and it can't help me to maintain my chemical at around 37.5 degrees without overshoot the water bath temp too much. And by adding another thermal tank takes extra cost and footprint to the whole system.

Again, thank you for the FAQ.
 
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PC Chen

PC Chen

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As Jerry Thirsty says always use a reliable, accurate thermometer to check the temperature of the measures. Always check inside the measures, not that of the heating water bath which can be 2-3 degrees warmer. I find for B&W I have to set the JOBO heater to approx 22c and for the C41 set it around 40c to get the baths up to the right temp. I tried it once as an experiment, setting the JOBO dial at 38c and leaving it overnight and in the morning the liquid in the measure after 8 hours was still only 36.3 degrees.

I use two thermometers (both Paterson) and find them quite accurate. They even agree with my thermal tank down to 0.1 degree which surprised me when I did the test. I am not after the brand but quite happy with them so far.
_DSF1897.jpg

Yes, I find that the actual temp is always lower than the setting; By how much is depend on the room temperature.

My problem is the water bath and the chemistry in the bottles can't be close enough even if I dial up the control. When I set it to 40 degrees the chemistry can reach above 37.0 but the water bath goes to 39.5 which is a little bit too high for C41. (I guess?)
 
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PC Chen

PC Chen

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The level of the bath has to be increased once the pump is running to get good coverage of the chemical bottles and graduates when using the trough, you just have to either add a short hose to the overflow outlet at the back of the processor or drain some water off when you turn off the pump as the water level will rise in the trough and may well come out of the overflow and go over the working surface or floor if not sat in a bath or container.

As I have mounted my CPP2 on a trolley to move it out of the way when I am not using it I have to be careful about the tank levels.

In order to have the highest possible water level, after the water bath fills I add more water to the trough until it starts overflowing a little bit from the back outlet. Even by applying this measure it can only covers about 2/3 of the Jobo 1L bottle, which only brings my chemistry to about 2~3 degrees lower than the water bath.

(Am I too critical?)
 

Ed Bray

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In order to have the highest possible water level, after the water bath fills I add more water to the trough until it starts overflowing a little bit from the back outlet. Even by applying this measure it can only covers about 2/3 of the Jobo 1L bottle, which only brings my chemistry to about 2~3 degrees lower than the water bath.

(Am I too critical?)

Yes, you are being a bit too critical. The norm is to set the Waterbath temperature to 2° above the processing temperature to allow for the difference in chemical temperature/cooling of the drum in use. If your Jobo needs to be set at 40.5° to give you a chemical temperature of 38° then so be it, or process at a slightly lower temperature and adjust the time to suit.

Merry Christmas.
 
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PC Chen

PC Chen

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Yes, you are being a bit too critical. The norm is to set the Waterbath temperature to 2° above the processing temperature to allow for the difference in chemical temperature/cooling of the drum in use. If your Jobo needs to be set at 40.5° to give you a chemical temperature of 38° then so be it, or process at a slightly lower temperature and adjust the time to suit.

Merry Christmas.

Thank you. I will definitely give it a try and share the result after Jobo again agrees to repair my new CPP3.
Please join the discussion, it needs your comments.

Happy holidays.
 

markbarendt

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I use two thermometers (both Paterson) and find them quite accurate. They even agree with my thermal tank down to 0.1 degree which surprised me when I did the test. I am not after the brand but quite happy with them so far.
View attachment 79015

Yes, I find that the actual temp is always lower than the setting; By how much is depend on the room temperature.

My problem is the water bath and the chemistry in the bottles can't be close enough even if I dial up the control. When I set it to 40 degrees the chemistry can reach above 37.0 but the water bath goes to 39.5 which is a little bit too high for C41. (I guess?)

I find that the water bath needs to be a bit warmer to keep the chemicals right. Depends on how fast you work. In the end the only thing that matters is the temperature of the chemicals themselves.
 

AgX

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I have a CPP2. It warms the bottles quite nicely, though it takes about an hour for them to come to temp and sometimes I cheat by nuking them lightly first, up to about 33C.

What to you mean by "nuking them lightly first"?
 

polyglot

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Hello polyglot,
I haven't had a chance to thank you personally. Your film FAQ really save me a lot of time from collecting info here and there.

I'm glad it's useful!

AgX: yes, microwaving. Since one knows the output power of a microwave and the specific heat capacity of water, it's pretty easy to raise a bottle by a desired amount without much danger of overheating.

I'm surprised that the CPP3 isn't heating bottles very well; is it a US (115V) or EU (240V) model and how powerful is the heater? My 240V CPP2 has a 1kW element and I suspect that some older models are lower power and therefore have less temperature control-loop bandwidth. If (and this is total speculation) for example all 115V models were 500W then they would have more trouble getting bottles to the right temperature without fluctuations.

I set 38C on my CPP2 and get about 37.5C in the developer bottle, which is quite good enough. Even E6 can happily be 2C out as long as you use an appropriate and consistent development time, and I suspect that no one does the fill-dev/dump/fill-stop dance quickly and accurately enough for a 1C error to be noticeable on typical chromes. Definitely not important for C41.
 
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