GPH/LPH is the standard pump rating but consistently misleading. Conversion: 1 GPH = 3.785 LPH. 100 GPH = 379 LPH. Why "rated" lies: pump GPH is measured at 0 ft head height (impossible in real installs). At 4 ft head (typical sump return), output drops 30-40%. At 6 ft, drops 50%+. Real-world examples: Eheim Compact 600 rated 600 LPH = ~400 LPH actual at 4 ft head. Sicce Syncra 5.0 rated 1,322 GPH = ~900 GPH actual. Sizing rules: calculate desired turnover (e.g., 5x for community FW), buy a pump rated 1.5x that GPH, install it, accept ~70% delivered. Dialed-down rule: oversized pump dialed down with valve = quieter, more reliable, longer life than maxed-out small pump. Solid pump brands: Eheim Compact (FW), Sicce Syncra (FW + SW), Tunze (SW), Red Sea ReefRun (DC controllable), AquaIllumination Nero, Jebao DCP/DCS (budget). Avoid: generic Amazon pumps (impeller failure within 6 months).
Reviewed by the Fast Aquatics husbandry team · Updated May 2026
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