When I had a HOB Overflow, I hard plumbed everything from the overflow to the sump. For the return I had everything hard plumbed also except for about 5 inches of flexible tubing connecting the pump to fixed plumbing in the sump. Made it easier for me to move the pump in the return chamber of the sump if needed without redoing any plumbing.Thank you for the info! Still kicking around different ideas. Next question.... Flexible hose? PVC? Or both?