Quick aquarium calculators

Fast checks for tank volume, substrate, filtration, water changes, nitrate dilution, heater sizing and conditioner dosing — without creating a saved tank.

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Tank volume

Length × width × height in cm.

Length cm Width cm Height cm

Litres0 L

UK gallons0

US gallons0

Substrate

Rough amount for sand/gravel depth.

Length cm Width cm Depth cm Kg per litre

Substrate volume0 L

Approx weight0 kg

Sand/gravel varies. Treat this as a buying estimate, not lab maths.

Filter turnover

Tank volume vs filter flow.

Tank litres Filter L/h

Turnover0×/h

Quick read—

Water change

Litres changed and nitrate dilution.

Tank litres Change % Current nitrate ppm Tap nitrate ppm

Water to change0 L

Nitrate after0 ppm

Heater guide

Very rough wattage guide.

Tank litres Room °C Target °C

Suggested range0 W

Temp lift0 °C

Use quality thermostats/controllers where possible. Big tanks usually benefit from split heaters.

Conditioner dose

Replacement water × dose per litre.

Replacement litres ml per litre

Conditioner dose0 ml

Example: 5 ml treats 250 L = 0.02 ml per litre.