As seen in attached pictures, there is a bubble forming in the tube connected to the reagent bottle, on the doser side. This bubble forms over a period of about 15 hours. It seems that the reagent is slowly flowing back into the reagent bottle.
The bubble then gets sucked into the KHD when the next measurement is made, (as can be seen in second picture) obviously resulting in wrong value.
The tube between the doser connector and the reagent bottle is 7cm long.

As it stands, I have to prime the reagent doser everyday in order to get correct measurements.

Also attached picture of my setup. Anything wrong there?

AirBubble_from_doser.jpg
AirBubble_to_KHD.jpg
GHLSetup.jpg