Return Pump GPH Calculator
A pump's rated GPH assumes zero head. Your plumbing isn't zero head. Get a rated-GPH target that accounts for vertical lift and elbow losses.
Your System
Sump water level to the tank's return outlet
Target flow at the tank
450 GPH
Effective head (equivalent feet)
8.5 ft
Buy a pump rated for at least
783 GPH
at 0 ft of head on the box, not the flow you actually need at the tank
Why this matters: Every foot of vertical lift and every 90° elbow costs real flow. This estimate uses a standard equivalent-length approximation (each elbow ≈ 1.5 ft of added head, roughly 5% flow loss per equivalent foot). Real pump curves vary by model, so check the specific pump's published flow-vs-head chart before buying at the margin.