Is there a chart that can tell me max gph on gravity feed pipe ID? Reason why I’m asking is because I have two 3/4” bulkheads and one 1 1/2” bulk head on my overflow. Want plumb my sump for good flow. Not sure if I use the 1 1/2” for the gate valved sump feed and ne of the 3/4 for my return and use the other 3/4 for emergency overflow.