PVC return to bulkhead

[TrailFish]

You will want to use a couple of unions and valves on each side of the return pump from the sump. When (not if) you need to service the pump you need to be able to easily disconnect. The valves are so you don't need to drain the sump or tank below the level of the bulkheads. Also, you should be sure that the sump can handle any water that may drain back from your tank in the event of a power failure (but you probably already know that). Good luck.