I have an overflow in the back left corner. My return comes out of the overflow box and has an elbow on it that is currently pointing straight down because a return jet that blasts outward was affecting flow of debris to the overflow box. I have one jet angled to the right in the middle-back of the tank, one in the right-back corner pointing towards the front-right, one in the front-right pointing towards the left, one in the front-middle pointing left, then one in the middle-left pointing towards the front. I think that all of these except for the last would tend to create a whirlpool around the tank going from the back left towards the right, then around the front and back to the left. I think youre right... I need to readjust the jets so that they all just point to the overflow.
What to you use to agitate the surface for oxygen replenishment? I could probably route the return to do this, but it would also disturb the flow towards the overflow unless I route the return to the opposite side of the tank (using 1/2" PVC or something).