Try redshift instead, you can use it from the terminal. If you want it to change according to time of day use redshift -l lon:lat. i.e longitude and latitude of current position. But you can also use redshift -O to set a specific level. I often use redshift -O 3500
Use redshift, its available in Debian so you can just apt-get it. There is a gtk interface (gtk-redshift) to help with configuration.
Note that in the latest version (1.8), the gtk-redshift launcher has been renamed to redshift-gtk.