Just saw the Cory question: the peppereds will do fine! At least until the geos get larger, but I would see them still working out, I just can't say from experience. Mine don't even look at other fish, just grab a mouthful of sand and mind their own business lol
I had three peppers in with mine, and even kuhlii loaches. They didn't bother anyone in my tank... angel, tetras, clown loach, kuhlii loaches, upside down cat, etc.