Hooking up a Jobo CPP2 to an Aquarium Chiller

EDIT: I fear I have posted this in the wrong forum. If a moderator wishes to move it to a more suitable forum, please do.

Hello All, long time listener, first time caller...

I recently acquired a new-to-me Jobo CPP2 processor with lift. I have a lot of experience hand developing and printing B&W but never with a rotary processor and I don't have any experience processing color - so expect a lot of questions.

The first question I have is in regards to connecting a chiller to the CPP2. I have a high capacity chiller that I used to run on a 70 gallon reef tank aquarium. When I sold the aquarium I kept the chiller for just this purpose, but thought I would have to plumb it to a separate water bath. Now I see I can plumb it into the jobo itself. I tried searching the forum and it seems like others are doing the same thing, but I'm not sure how? I assume I will need to run and in-line pump between the chiller and the jobo, is this ok to do with the solenoid? What type of pump are others using? I'm curious as to how others have set this up.

Also, I've been reading threads about rotary processing of both B&W and color and many of the old threads reference internet sites (for data) that no longer exist. Are there any good sites that list times/chemistry volumes for rotary work?

I look forward to learning more about this process and spending a great deal of time here.

Best,

Matthew Cherry

I'm shooting Tri-X in either HC-110 or D76 straight. T-Max 100 in T-Max developer. Delta 100 and HP5 in Ilford DDX, and sometimes D76 or HC-110 for the HP5.

A Jobo CPP2 has a cold water intake on the back-left part (looking at it with the switch at your left).
You don't need an additional pump.
You set the desired temperature with the knobs in the front, for colour development that would be presumably some "lines" above the canonical temperature. Canonical temperature is 37.8 °C so I set my Jobo at 38.3 °C. I use the "lift" so my tank has a hole on top whereby ambient air enters so I keep the system temperature a bit above the canonical temperature. Your mileage may vary.

The heater heats the water to around 38.3 °C and the internal thermometer feeds back the heater switch. If your room temperature is below 38 °C (hopefully!) you shouldn't need the external water intake. I let the Jobo run (pump and heater on) for 1 hour so that all the plastics, the chemistry etc. is at the right temperature when I begin developing and the "system" temperature becomes decently stable.

The external water intake is typically used when using the Jobo for processing Black / White at "low" temperature during Summer. Supposing you want to develop at 20 °C, but your room temperature and your Jobo are at 28 °C, you need a way to cool your Jobo. Supposing the water coming from the external intake is cold, the Jobo uses the water intake to keep the temperature firmly around 20 °C.

In theory you can connect the external water intake also for colour, but in my experience this leads to more ample "pendulum swings" in the water temperature.

For the same reason, if you happen to develop B&W in a room with a temperature of 15 °C you don't need the cold water intake and proceed as outlined above in the case of colour development.

The temperature is basically the same with rotary processor and with manual inversion.

The amount of chemistry is smaller when using a rotary processor. Refer to the Jobo site or just read the volumes on the label sticked on the outer part of the Jobo tanks. If your Jobo tank doesn't have the sticker with the volume ask a question here.

The developing time is probably slightly higher. You'll have to do your tests to determine the correct time. I use 7'30" for the first run of chemistry, and 8'10" for the second run, with Fuji Astia and Fuji Sensia (slide film, E-6 treatment).

With colour negative film, C-41 treatment, my notes say 3'15" first run, 3'23" second run, those times are given including the draining time and the small natural time you need to begin pouring the subsequent bath. So for 3'15" you should set your stopwatch at 3'00", turn it on immediately after pouring, and start draining when the stopwatch rings. Those are my times and I use the accessory Jobo "lift". Your times may vary.

It is imperative that the tank is perfectly horizontal to guarantee evenness of development. Horizontality must be checked on the tank not on the Jobo.

It is also imperative that you fill the tank with all the reels even if some of them are empty. If you develop only one roll in a tank for two reels, put inside the tank one reel with the film and the other reel without the film.

Feel free to ask any question.

Welcome in the stinking-hands club (ok now that I think about it in your case the stinking-hands bit is since long acquired).

Fabrizio

I have a CPP-2, and here's how I use it in hot weather.
1. Fill the tub.
2. Fill a clean bucket with cold water, and drop some ice packs into it. Using some tubing, hook an aquarium pump up to the Jobo cold water inlet, and put the pump in the ice water.
3. Set the temperature and develop as normal.

The Jobo will add cold water as the water temperature in the tub rises. Be sure to hook some hose to the Jobo's overflow spigot, unless you have the Jobo in a sink.

Fabrizio,

Thank you! I am hoping that with the Jobo, my hands will start to stink less!

I already have an aquarium chiller that (I think) has a built in pump. I assume I can plumb it into the jobo (both intake and overflow as the chiller is a closed, recirculating system) and just not turn it on when doing color work?

Brian, thank's for the response. It's good to know that I can hook a pump up to that line if necessary. I assume you do the same thing and just make sure the pump is off when doing color?

I usually don't have issues, but when I do need to cool things down, I have a couple of the 1L jobo chemistry bottles, filled with water that I keep in the freezer - if I put those in a couple of the chemistry cells, I find that it can keep the bath at 20C for long enough to develop several batches of film. I keep the ice-bottles as far away from my developer as possible so that there is not a local cooling effect.

Matthew Cherry said:

I already have an aquarium chiller that (I think) has a built in pump. I assume I can plumb it into the jobo (both intake and overflow as the chiller is a closed, recirculating system) and just not turn it on when doing color work?

Click to expand...

The Jobo will open the water inlet from time to time when the measured temperature diverges from the target temperature so while doing colour work if the water falls from the chiller by gravity the best option is to close the tap bringing water to the water inlet, or just disconnect the water inlet entirely, because this intake of cold water will actually amplify the temperature variations in my experience.

Diapositivo said:

The Jobo will open the water inlet from time to time when the measured temperature diverges from the target temperature so while doing colour work if the water falls from the chiller by gravity the best option is to close the tap bringing water to the water inlet, or just disconnect the water inlet entirely, because this intake of cold water will actually amplify the temperature variations in my experience.

Click to expand...

See this is what confuses me. If the jobo uses a solenoid that opens when the water bath needs to be cooled, why disconnect the chiller feed line?

Because when the solenoid opens and the cold water enters it takes a while for its effect to be felt on the thermic system or, more simply, at the thermometer. When the thermometer "feels" the cold water and cuts its inflow, "too much water" is already in the system. Now the solenoid is closed, but in a short while the cold water will be mixed with the warm water and the water temperature will be, let's say, 37.3 °C.

If the cold water is disconnected, let's say you set 38.3 °C, the temperature will oscillate let's say between 38.0 and 38.6. You will notice the value will change quite fast, with short "peaks" and then go back to normal. This is, I think, because the water doesn't mix very well inside the Jobo, some water near the heater forms some "zones" of high temperature which make the reading raise for a few seconds before going back to normal.

At let's say 38.6 the solenoid opens but if you disconnected the cold water there are no consequences. In ten seconds the display will indicate 38.3 again and all will be right. Those short peaks in displayed temperature will depend from less than perfect mixing of water near the sensor.

If the cold water is connected during those 10 seconds "a lot" of cold water will enter and the system will have been unnecessarily cooled, then the soleinoid will close but now the heater will take some time to bring the system back to 38.3 °C. If there is a sudden trip to 38.6 the solenoid opens again...

Best way of operating is: if the bath temperature is above the ambient temperature, the heater is enough to control temperature IMO. It will go on and off and the temperature will tend to lower when the heater is off, with a gentle "feedback" between heater and thermometre.

If instead the cold water is connected the Jobo will act with "jerks" reactions: sudden peaks of high temperature will cause cold water to enter the system causing sudden falls of temperature. It will take more time and more money to put all the system in temperature because the Jobo will from time to time allow cold water to "undo" the heating work so far done, and it all becomes a Penelope's shroud.

AHA! Thank you so much for explaining it to me!

Hello,

I'm reviving an old thread because, well, if you've seen my other thread, you know that I've procrastinated using the JOBO for B&W development. But I'm keen on changing that if possible.

So, having read the fantastic replies here on how the cold water solenoid works on the unit, I'm thinking about just bypassing it all together and pluming in my own inlet and outlet into the base of the unit. Both inlet and outlet would have ball valves that could be turned off. For the inlet side, I would put an aquarium pump between the chiller and the JOBO. The outlet would gravity feed back down to the chiller.

In this way, I can set the temp on the chiller unit (which is very precise and stable) and turn the heater on the jobo off and just allow the chiller to control the temp of the water bath in the JOBO during the summer months.

Does this make sense, or am I trying to solve a problem that doesn't exist when I could simply develop at 75 instead of 68? I would like to have year round consistence in my negatives and have always used ice to regulate the temp when doing hand development. I have also considered plumbing the chiller into the sink for hand developing, but if I can get negatives I like out of the JOBO (yet to be decided) I would rather just go this route.

Matthew Cherry said:

Does this make sense, or am I trying to solve a problem that doesn't exist when I could simply develop at 75 instead of 68? .

Click to expand...

In my experience, the temperature in my darkroom is rarely much above 20C, Even when the outside temperature is over 30, inside it is somewhat cooler. The issue is that when the tap water is warmer than 20C, the unit can't cool it down, and in that case, just putting a 1L bottle of ice in the tempering bath quickly brings the temperature down to 20, and the thermostat and heater then hold it at 20. Unless I have a huge quantity of film to develop, the 1L of ice keeps me at temp for plenty of time to get several batches of film developed.

So for me - it really isn't an issue. Perhaps if I lived in a warmer climate it would be more of an issue.