"Sous-vide" it is a cooking method where food is placed in a plastic bag and then cooked in a water bath like this, at an accurately regulated temperature. Chocolate tempering is all about temperature accuracy, I should have thought about this in the first place. I did not, I am a human being after all.
The chocolate tempering curve is
1- Melt everything at 50°C - 122°F
2- Go down to 28°C - 82°F
3- Back up to 32°C - 90°F and stay there as long as you want.