You will need
  • roulette
  • pencil and paper
  • calculator
If your aquarium is a parallelogram, you need to measure the width, depth and length of the outside and record these values.
Now you have to calculate the internal dimensions. To do this, measure the thickness of the wall of the tank, multiply by two and subtract the resulting figure from every dimension. For example, the thickness of the wall of the aquarium of 0.5 cm. You'll need to subtract an inch from the external length to find the inside length.
Translate centimeters to meters and calculate the volume of the aquariumusing internal measurements. Multiply the length by the width and height and you will get the volume in cubic meters.
Now turn the cubic meters to liters. One cubic meter is one thousand liters.
Take a standard 50 gallon tank with a wall thickness of 0.5 centimeters, and the following external dimensions 54х27х35 inches. The internal dimensions will be equal 53х26х34сантиметра. From each measurement we subtracted 1 centimeter, the thickness of the wall of the aquarium, multiplied by two. Its volume in cubic meters will be of 0.54 x 0.26 x 0.35 = 0,0491 centimeter or 49 liters.
It would seem that the difference of 1 liter is not so significant, but this amount corresponds to the amount of water noritomo in the tank to the brim and only if in the tank nothing else. If we don't fill up with water to the edge of the aquarium is 3 cm, the water still 0.5 litre less. How do we know it? Multiplying the area of the bottom to a height from the water surface to the edge of the aquarium, i.e. 0,54х0,29х0,03, and translating the resulting figure – 0,0042 – cubic centimeters to liters.
Now you can take about a liter of water to the volume occupied by the filter and the heater. And is around 0.5 litres on the driftwood or other decorations. And don't forget the algae. And there is still primer! 2 cm basalt crumb is about 0.8 liters of the total volume. So your 50 gallon tank actually holds about 47 liters. And the larger the tank, the more noticeable the difference between the stated volume and the actual.