Plumbing... Need help

[possitive k]

pvc sch 40 is what you need, corix is the best place for this. however like said before , increasing pipe size is not necessary. increasing pipe size will give you the same volume at a lower psi, make sure you install a check valve. your volume will be determined by your pump.

[mark]

put some thought in your return layout and sump size to see if you can avoid using a check valve