When I first started cooking sous-vide, the holy grail was temperature accuracy and stability. I think this is very important for certain applications such as eggs, and for professionals and sous vide geeks. However, if you are a general home user, I don't think accuracy and stability to within 1º is of the utmost importance.
That being said, I know this is important for most of the regular readers of this blog. Unfortunately, I have a job and I don't own a high quality data logger (*), so I am not able to give you a super accurate reading on the temperature of the water bath. I will tell you that I recently ran a 136ºF short rib from one to three days inside of the SousVide Supreme Demi. I checked in to see what the readings of the SVS Demi's PID controller, and would see it vary from 135F - 137F. I confirmed some of these readings with digital thermometer that was rated with +/- 1ºF accuracy.
That being said, I want to rerun some tests to see if I can get different results. For example, I ran the device with the water being filled up to the fill line and not to the max line. With more water in the device, I might have seen more stability.

Since I wanted to test long term stability, I figured I would run another test I have been wanting to do for a long time. One short rib, same temperature, three time periods. How does this all work? Easy:
- Set SousVide Supreme Demi's temperature to 136F. Will convert collagen to gelatin slowly, keeping meat medium rare.
- Drop three slices of the same short rib at 24 hour time intervals. Each short rib had zero additions (no fat, no salt).
- Remove bags at same time. Now I have 24 hour, 48 hour and 72 hour samples.
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Sous Vide Short Rib Exteriors |
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Sous Vide Short Rib Interiors |
(*) Does anyone have any recommendations on a good temperature data logger? Ideally, I would like something like the Voltcraft K202, but it isn't available here in the US.