Hydro Habitats Guide Library
Aquarium Tools
Use these calculators to plan aquarium volumes, interpret flow, and convert water-test units. Results are estimates or unit conversions—not livestock prescriptions, pump guarantees, or structural approval.
Sump Power-Off / Reserve Calculator
Estimate display drain-down from the planned water-level drop, add any separately estimated plumbing drain volume, and compare it with the sump's unused space up to its safe maximum level.
Estimate
Assumptions and safety: Display drain volume uses a rectangular footprint and uniform water-level drop; substrate, rock, overflow and plumbing geometry can change actual drain-down. An entered extra allowance is added to the estimate. Sump reserve is its rectangular footprint between the operating and safe maximum levels. Test the complete system by switching off the return pump and verifying the result in person. Return outlets, siphons, overflow design, plumbing geometry, check-valve behavior, and equipment configuration can drain more than expected; a check valve is not a substitute for reserve capacity or testing.
Return Pump / Head-Loss Estimator
Estimate an operating point only from flow/head points on your specific pump's manufacturer curve. The tool approximates the curve linearly between the points you enter and solves where it meets an estimated plumbing system curve.
Estimated operating point
Limitations: This is a planning estimate, not a universal pump curve or measured flow. It uses Darcy–Weisbach pipe and fitting losses, a general friction-factor approximation, water properties near 20°C, and linear interpolation only between user-supplied manufacturer data for the same pump/control setting. It assumes a simple return path; valves, filters, manifolds, dirty equipment, unusual fittings, and measurement error may add losses. If no intersection lies within the entered curve points, add suitable manufacturer data; the tool will not extrapolate. A flow meter or measured pump data is more reliable.
Alkalinity Unit Converter
Convert one alkalinity result among dKH, milliequivalents per liter (meq/L), and parts per million as calcium carbonate (ppm as CaCO3). This is a unit conversion, not a dosing recommendation.
Equivalent alkalinity
Conversion basis: 1 meq/L = 50 mg/L as CaCO3; 1 dKH = 17.848 mg/L as CaCO3 (therefore about 0.357 meq/L). ppm is treated as mg/L for these dilute aquarium-water measurements. Test methods and what they measure can differ; use the unit stated by the test or instrument.
Aquarium Filled-Weight Estimator
Estimate water mass from actual operating water volume—not the aquarium's nominal label volume—then add the weights you know for the tank, stand, substrate, rock/decor, and equipment.
Estimated operating weight
Structural limitation: At approximately 20°C, freshwater is estimated at 8.33 lb/US gal and standard-ocean saltwater at about 8.55 lb/US gal. Actual water density varies with temperature and salinity. Enter actual operating water volume and known component weights; zero-valued component fields are excluded if their weight is unknown, so the total may be understated. This calculator cannot determine whether a floor, stand, or building structure can safely support the aquarium. For significant loads or uncertain structures, obtain a qualified structural evaluation.
Water Change Calculator
Calculate the volume to remove and replace for one chosen water change. Use a realistic estimate of actual system water volume, which can differ from nominal tank capacity.
Single water change
Assumptions: A single change removes and replaces equal volumes, leaving the system at its starting water volume. “Original water remaining” is the ideal well-mixed remainder immediately after that one exchange; this tool does not prescribe a percentage or estimate pollutant changes. For a sequence of changes, each exchange acts on the remaining concentration rather than adding percentages.
Aquarium Turnover Calculator
Calculate turnovers per hour from system volume and actual or estimated flow, or calculate the flow corresponding to a selected turnover rate.
Turnover estimate
Interpretation: Turnover is flow divided by system volume. It describes nominal hourly volume movement, not how evenly water reaches livestock or surfaces. For reef systems, sump-return turnover and separate powerhead/wavemaker circulation are different flows; do not add them or treat a turnover figure as a universal ideal.
Methods and References
Equations and conversion constants are standard dimensional or engineering relationships; the estimation limits are stated with each tool.
- Losses and Friction Factors NPTEL fluid-mechanics lecture; Darcy–Weisbach head loss and friction-factor context.
- Friction-Factor Equation Spans All Fluid-Flow Regimes Stuart W. Churchill, Chemical Engineering, 1977; original friction-factor correlation.
- Total Alkalinity U.S. Environmental Protection Agency; alkalinity reported as calcium carbonate equivalents.
- Alkalinity and Acid-Neutralizing Capacity U.S. Geological Survey technical reference on alkalinity units and equivalents.
- Facts About Water U.S. Geological Survey; freshwater density context.
- World Ocean Database 2018 Notes NOAA National Centers for Environmental Information; standard-ocean seawater density convention.
- Thermodynamic Properties of Water National Institute of Standards and Technology; IAPWS formulation and freshwater density by temperature.