Hi Matthias,

Thank you for your reply.

I changed the Profilux wall plug to a different socket (I had all my tank electronics connected to the same socket) and that changed the PH figure to 8,2 in Profilux (when not connected to the pc). Now that is the correct figure, i am after. However, again, when I connected the Profilux to my pc with the usb cable, I am getting a different reading (9,2). So there must be something causing troubles with the connection to pc? Can it be the cable or the software? Or is my pc causing the interference? This is very odd...