Hey Matthias,
thanks for your quick reply.

Just to be sure:
When I do it on the Controller itself and go to temp -> callibration and confirm the controller immediately asks for " save settings" Yes or No. When I select YES nothing really changes and the Temp. is still about 1 degree off.

I guess with the "calibration" in the software you mean:
"Adjust Temperature" in the Temp section?
As I think to remember all the settings have to be done in Celcius even when using Fahrenheit as a display?
Therefore I converted the
Profilux temperature display: 80 -> 26.7
Thermometer display: 78.5 -> 25.8

So technically if where it says "I want the temp reading to be" ..... lowered or raised I should put in "0.9" and then select LOWERED.
When this is done the Controller will activate heaters etc based on the NEW values?

Hope that makes sense?
Michael