Hey, I am a sound guy at a very tiny church, I am hoping that one of you may be able to help me figure out how to send fx through a mix, but not through the mains. Thank you!
I am running the Qu-24 board 
turn off the FX returns from the main bus
Assign button on the left side of the desk and the select buttons of the channels toggle between on/off for routings
https://www.allen-heath.com/media/Qu-Mixer-Getting-Started-Guide-AP10025_2-V1.9.pdf
on page 19
Thank you!