I assume you are referring to the pre-1945 period. 

Originally green as well as red was used. In the mid 1930s the tracer started green and at about 500 m switched to red. After this period, yellow started to be used and from 1941 orange.

Luftwaffe from 1941 mostly used white. A special "100/600" remained dark up to 100 m and then traced to 600 m. Ordinary trace was up to about 900 m 

The above is from the standard book on German 7.9 mm by Windisch/Micke/Kellner.  

TY