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Weights and Measures

Question: How much does it hold, and how heavy is it when full?

Answer: If you are "European" and work in Metric, then things are relatively straight forward, its only if you're a golden oldie like myself and still use feet and inches that things get a little complicated.

In the metric system everything has a clearly defined relationship all based around, believe or not, water. At 25°C 1 litre of water weighs 1 kilogram, and as there are 1000 cubic centimeters in 1 litre and 1000 grams in 1 kilogram, 1cc of water weighs 1 gram. If for example someone asks how heavy is a Rio 180 aquarium when full, then the answer is easy, 180 litre weighs 180 kilograms + about 30 for the glass tank.!

Perhaps the most important question is how do we calculate how much water a tank might actually hold, but again the answer is quite simple.


Volumn (in litres) = length x width x depth (in metres) x 1000


If we use this with the example Rio 180 aquarium that I mentioned above then the length = 100 cm, width = 40cm, water depth = 45cm


1 (length) x 0.4 (width) x 0.45 (depth to water level) x 1000 = 180 litre


The same is true for ponds and pools, although it not very often that we find a pond with such clear-cut shapes or dimensions. In most cases you will need to make a sketch and divide it into smaller more regular shapes to get the most accurate calculation.

Those of you working in imperial need to know two more pieces of information, 1 cubic foot = 6.25 gallons, and 1 gallon = 4.5 litre.


Length x width x depth (in feet) x 6.25 = volumn in Gallons

Volumn in Gallons x 4.5 = Volumn in Litres



Maroon Clownfish in an Anemone