Hello!    
I'm using 2 screens, the 2nd one is for mfcd/shkval and its always red in FC3 modules (and Su-25t), shkval got a little red tint too when its on. I was looking thru the files to find something responsible for this but with no luck. 
When flying BS2 i don't have any problem, it's always black when off and no tint whatsoever.   
I was searching for this issue some time ago and found some dated posts about this but without any solution. Does anyone have this issue or found a way to fix this?   
Here's monitor setup     
and some screenshots