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Aquarium tool

Aquarium volume calculator

Work out how much water your tank really holds, and what it will weigh when full.

Tank shape
Measuring in
Those sizes were measured

Water when filled

litres

That is US gallons or UK gallons. The full shape of the tank holds litres, the size most labels use.

Weight when full

kg before wood, rocks, and equipment

  • Water kg
  • Substrate kg
  • Glass kg

Check that your stand and floor can carry this. A stand needs to support the whole base evenly.

Putting it to use

  • A 25% water change litres
  • Filter flow to aim for L/h
  • Heater, in a normal roomAbout W

Dose treatments and conditioner on the water figure above, not on the labelled size. Wood and rocks take up more space, so the true figure is a little lower. Filter and heater figures are common rules of thumb: 4 to 6 tank volumes an hour, and about 1 watt per litre. A cold room needs more heat.

Why the real figure is lower than the label

A tank sold as 60 litres is usually measured around the outside of the glass and up to the rim. The glass takes up space, substrate fills the bottom, and few people fill right to the top. It is common for a tank to hold 15 to 25% less water than its label says, before you add any wood or rocks.

Why it matters

How accurate is it?

The result is a close estimate. Substrate is counted at 1.6 kg per litre, which suits gravel and sand, and glass at 2.5 kg per litre. Bow-front and corner tanks vary between makers, so treat those two shapes as a good approximation. For a medicine dose where accuracy really matters, count the water as you fill the tank.

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