Sous-Vide

Steven Lee said:

@Donald Qualls An engineering/efficiency geek in me instantly activated upon seeing your message! Some rough calculations: heating 5L of water by 18C takes about 90kcal or just about 0.1Kw/h. This is about $0.017, taking the average energy cost in the USA. That's what you're optimizing: for the most efficient way to spend less than 2 cents.

I would argue that your central heater is more efficient than sous vide because it may be using a cheaper energy source (gas in many states) and it is insulated. Meanwhile, a sous vide will be fighting the temperature loss due to ambient and driving the pump. I also don't see how any water is wasted? It's trivial to fill up the tub with water of desired temperature, and it will be well-mixed too. Just open the hot faucet and start filling up the tub. Eventually it will get hotter, then you open the cold faucet, and you're done. Not a single drop of wasted water. After a while you won't even need the thermometer, because 110-115F feels just slightly warm and you don't have to be precise.

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Not trying to be rude, but that might work if you don’t live in a 100 year old house that had its plumbing done by a guy with a blowtorch in one hand and a beer in the other . In the winter it can take several minutes of running the water to get to the hot stuff, which may not bother a bathtub full or you but is definitely not super efficient. Even in the summer I am dumping a lot of water down the drain to get to hot, so if you care about water usage that can be a problem.Everyone needs to make a decision based on what matters to them.

I enhanced my Jobo CPE-2 with a sous vide because it is far more accurate and precise than the built in thermostat. It also provides a temperature homogenity that is far superior to the convection style heater.
Being a precision fanatic myself, i did extensive testing with an reference thermometer and found a temperature homogenity and stability error of <0.1K, which is pro-lab-grade to me and it can be set by numbers, not by
a coarse knob with pracically no scale.

So, this was a very cheap add-on for me, but one of the most useful. It frees my mind from worrying about the temperature stuff, provided that careful initial tuning is done. Bottles create some temperature drop
by conducting heat away via their tops that are in contact with air, same goes for the development tank itself. Everything is in the sub 1K range, but for color, we want to be more accurate.
One just has to measure the temperature over time in the tank in appropriate intervals over about 8min to get an idea if the effective processing temperature is within spec. At the end of the day, the temperature of the
developer in the thank is what matters and not the water jacket nor the temperature in the bottles.

Before the Jobo, i used the sous vide in an bucket, also worked great. Homogenisation and stability is the key.

Fyi i mostly do E6 and the sous vide is the one from Cinestill.
I can highly recommend such a device and a process thermometer. It enables very good and tight temperature control with low cost.

Photomultiplier said:

Fyi i mostly do E6 and the sous vide is the one from Cinestill.
I can highly recommend such a device and a process thermometer. It enables very good and tight temperature control with low cost.

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FWIW, if you're trying to control costs, you can get a unit with identical specs for about a third the money from eBay sellers. That's where I got mine, for less than US$40.

I know, but i didn't know back when i bought the unit. Never heard from such a device before, so i just bought it with a lot of other supplies at my photo dealer.
Found out later that a "normal" stick is also sufficient

Understood, but still potentially helpful to others reading this thread to research a purchase.

Photomultiplier said:

I enhanced my Jobo CPE-2 with a sous vide because it is far more accurate and precise than the built in thermostat. It also provides a temperature homogenity that is far superior to the convection style heater.

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So I guess I didn't invent anything revoulutionary then. Darn. But I do think this is much more precise than the guess-o-matic dial. I have mine set to 106* (41ish?) as I was running an experimental ECN2-ish run of film.