Who Gives A Fish Forums

I'm new to this, but my LFS said they'd be fine together. Now I'm nervous. Should I move one? They're about 3 inches apart in my 40-gallon.

Thanks for the input, everyone. Gonna give 'em some more space and keep an eye on the sweepers. My alk's at 8.5 dKH, calcium 420, and nitrates around 5 ppm. Flow's moderate, with two Nero 5s. Appreciate the help!