Hello, I just got a beseler 23C III not too long ago. I’ve always done my darkroom stuff in classrooms so everything was mostly set up for me. Now that I’m entering the world of at home enlarging I’m realizing there was a lot I didn’t know about. I have the Variable Contrast Head, and I realized it has mixing chambers. Now I was lucky enough to get the both the 6x9 and the 35mm when I bought the enlarger, but I’m only going to be shooting 35mm and 6x7. Do I need to buy the 6x7 mixing chamber?