sump question?

[rayviv]

I need to drill holes in the return lines and not sure what size. These are the lines that deliver the water from tank to sump over the floss. I hope to be running two pumps at between 500 to 700 gph on each.

Also need to drill holes in the skimmer return line in a way that will spin/roll cheeto in sump. Any suggestions?
Ray

[marinelife]

1" is usually good for 600 GPH of flow.

[rayviv]

Thanks