Update: Thursday evening i come home from work and the circuit to the return pump has tripped again. This circuit is tied into the main circuit for the whole fish/basement room.
One of two things is going on here. One, the whole circuit is near capacity because of the additional light and pumps to the frag tank or Two, the GFCI at the switch for the return pump is weak and the ATO switch kicking on causes it to trip.
Either way i'm making changes tomorrow. One i'm replacing the GFCI. Two i'm splitting the main circuit into two separate circuits.
So tomorrow i'm off to Lowe's for a main 15 amp breaker, GFCI, Some wire nuts and hog nose nails. I've got plenty of 14/2 wire. This should solve my issues.