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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Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.
Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.
Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.
Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.
Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.
How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.
What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.
How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.
Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.
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