I may be entirely daft here - it's likely, but I have my space station set up, with its fuel tanks.
I have 3 tanks for monopropellant, and 3 tanks for Liquid fuel and oxidizer. I filled them all up at launch with monopropellant. Now 3 are empty - i want to convert these empty tanks to hold Lq and Ox. How do I make it do this as it won't let me transfer LQ and OX into them
Below is a picture hopefully explaining what i mean...
P.S. I have interstellar fuel switch installed.