I do not know anything about Phototherm, except what I can read and see on the web. So I cannot comment on that.
As for colour processing, and in particular C41, it really is a quite easy process. The more you control the process, the better (technically) your output will be.
I have been running a Jobo CPE2 processor for around 28/29 years. This was the lowest of the units available and the only one I could afford at the time. It still works and I still use it, in fact I’ll be using it tonight when things cool down to process some more film (B&W).
Now you may wish to start processing without any kind of processor, it really is that easy. However if you ramp up production then having a machine to take some of the possible errors, not to mention a certain amount of drudgery, then go for it.
Whichever way you go, think of the future. If you try out C41 and keep on doing it in low numbers, then normal inversion processing without any machinery is perfectly acceptable and in reality, very good.
I think the wide lipped Patterson tanks that are the latest incarnation of Patterson tanks are about the best and easiest to use, especially as the top acts as a big and easy to use funnel. They are relatively cheap to boot.
If you are thinking you may eventually go the machine route, then Jobo would have to be in the equation. One needs to understand the Jobo tank system then decide how to do it.
I would suggest you could look at picking up a Jobo 1540 tank, this can process 4x135 films or 4x120 films. The 1540 is really a 1510 tank (1 roll of 135 film) and a 1530 extension, which must have the 1530 extension core to be able to be used.
This tank uses (in round figures) 500ml of solution in a rotary situation and is about the easiest Jobo tank to use in a rotary method without a machine. Trust me I have done this squillions of times, well, maybe a few hundred, but who’s counting. If you decide to use inversion processing with this tank, then in round figures you will require 1 litre of solution for the same amount of films.
My take on the C41 process is that 1 litre of developer solution will process 8 rolls of 135 or 120 film in a one shot developing situation. So you can do either 4 rolls at a time and use 500ml then do another 4 rolls with the other half of the 1 litre of developer solution. Or, you can process 4 rolls at a time twice re-using the whole 1 litre twice. My take on that is to process the second lot of films within a couple of hours of the first processing.
To process in a rotary sense without a rotary processor is simple with this tank, you just roll the tank sideways (if you wish in a water bath) on the bottom of a flat surface, I use my darkroom sink for this. This is a link to a 1540 tank ready to be rolled.
https://www.google.com.au/search?q=jobo+multi+tank+1540&client=firefox-b&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjn2ebmu5jRAhVEX5QKHYiLDQoQ_AUICSgC&biw=1536&bih=732#imgrc=0K_0vvKduPxvcM:
As for a machine processor, I would suggest the cheapest solution would be one of the Jobo systems. The CPE2 is the oldest and is perfectly capable of a lot of work, as long as it hasn’t been overloaded. Or run into the ground, both of which are always possibilities.
Whichever unit you pick up (if you go Jobo that is) I would suggest getting one with a lift, they are virtually mandatory for the C41 process as it is the shortest standard process that I know of, at 3’15” for the colour developer. Having the lift enables you to time the pouring out of the developer so that the tank is empty at exactly 3’15” and at 3’16” you can start pouring in a stop bath (2% acetic acid solution).
A stop bath is not included in the official process, but it has two advantages, firstly, it stops any development virtually instantly. Secondly it certainly helps to keep your bleach and fix baths cleaner. Blix, which is a combination of bleach and fixer baths, and is a trade name, is certainly acceptable and as far as I know perfect. I however, run a bleach bath and a fix bath.
Running a stop bath after the developer bath also allows you to take a deep breath, slow down and concentrate on the remaining steps. This will be less of an issue as you progress and continue to learn C41 developing.
If you are not going to use sheet film, and I’m primarily talking about 4x5” film here, then any of the Jobo 1500 series of tanks will be able to process any combination of 135 and 120 film perfectly. That said, the 1540 tank is the stand out tank.
As time goes on you can add to your tank situation. The first addition I would think about would be the 1520 tank. Which can do 2x135 rolls or 2x120 rolls. The 1530 module can be added to the 1520 tank, which will allow you to process 5x135 rolls or 6x120 rolls. I do however, suggest you do not use this combination (1520 tank plus 1530 extension) on the CPE2 unit, it certainly puts strain on the small(ish) motor.
The Jobo CPE2 is the baby of the system, it comes with virtually no extras that can fail, like water pumps and electronic sensors. In that sense, it is something that, as long as the motor keeps working, should be a long time running.
Any model above the CPE2 is pretty good, certainly better in some aspects, but they come at a price, they are increasingly bigger and of course more complex, but they are nice.
With the CPE2 you can process films easily and professionally for the 135/120 and 4x5” formats. You can process up to 8x10” sheet film, but a bit of fiddling by using a print drum is what I have done. Do-able, but not the greatest.
The next processor up is the CPA2 unit, this was probably their best value for money if you were a professional photographer doing a lot of work and shooting sheet film. It can take the Expert film drums, which are the bee’s knees for evenness of sheet film processing. I have used a CPA2 unit and must say I was envious of the photographer who owned it.
Study the Jobo tank system and what can be used with what chemistry and on what machine, then if you wish to go ahead, choose an appropriate Jobo processor for the tanks and films you wish to process.
Whatever you do, if you do, do, get one with a lift.
Mick.