CALCULATOR
Tank Volume Calculator
Nominal volume is not water volume. This accounts for glass thickness, substrate displacement and hardscape, then sizes the filter and heater to match.
Inputs
Gross volume (L)
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updates as you type
Actual water volume (L)
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Substrate required (kg)
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Filter turnover (L/h)
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Heater wattage (W)
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Gross volume is the inside dimensions of the glass box. Actual water volume subtracts substrate displacement, hardscape and the 2–3 cm freeboard every rimless tank needs.
Filter turnover targets 4–6× the actual water volume per hour for a planted tank and 6–10× for a fish-only tank. The figure given is the effective flow you need, not the box rating.
Heater wattage follows the rule of roughly 1 W per litre for a 5 °C rise above room temperature, doubled for a 10 °C rise.
Note. This calculator is a simplified model built on conventional ranges. It is not a measurement of your tank, and no outcome for any plant or animal is guaranteed. Confirm every figure with a test kit before acting on it.