Plumbing return and supply question???

[Wildblue4]

On my new build 250 Marineland, it has 4 predrilled 1” bulkheads. It came with 1 1/2” returns reduced to the 1” bulkheads. Then1” into the sump. From what I can tell they had flexible 1” tube to a hose barb to the 1” bulkhead and 1” into the tank for the supply. I would like to hard pipe PVC so would 1” pipe be ok for both the sump return and supply, with the sump pump a 3/4” discharge and the 1 1/2” returns in the overflow box? Or should I use 3/4” all the way from sump pump to bulkhead and 1” into the tank?

 

[don_chuwish]

When you say 1 1/2" 'returns' I think you mean drains, correct? And by 'supply' you mean return (returns to tank). If I have that right then it sounds like they were setting up for a Durso style drain.

Overflow Boxes and Drain Styles - Durso, Herbie, and Bean Animal

Decide which of the three most common types of drains and overflow boxes is right for you and your tank.

blog.marinedepot.com

For the return lines you can go 3/4" off the pump right up to the bulkheads, reducer to fit the bulkhead, then another reducer to fit 3/4" in the tank. Or just use 1" from the bulkhead up. For the drains you can do 1" all the way just fine.