Figuring Out Litres/gallons Of An Octagonal Tank

fishlette

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ive just decided to get the last octagonal tank at work for something small and easy to look after at home as i have too many harder to look after stuff :)

im not sure how to figure out the litres/gallons of a tank this shape. all it says on the tank is 46cm. does anyone know how to figure this out?

also depending on volume, what are some ideas from people for inhabitants? my thoughts were a small shoal of neons, 2 blue panchax and a bristlenose or a couple of corys probably pygmies. its going to be a planted tank but with what i dont know. prob some dwarf species and some aluminium maybe not sure yet.

this is my first small tank and its hard to figure out what to put in there :)
 
Measure the height and then measure the distance from side to opposite side on the flat sections and then from side to opposite side on the points.

If you take the average of the two side-to-side / point-to-point numbers, you will have diameter of the tank if it was round. Then use this site to figure out your volume based on a round tank/pond.
http://www.fishpondinfo.com/calc.htm
 
An Octogon is basically a square with the corners chopped off.
Each corner is 4 triangles, 4 triangles added together = 2 squares.
So the area is a big square with 2 little squares removed from it.

Let's assume that 46cm refers to the overall base width (& therefore length),
this would otherwise make a square whose area would be 46 x 46 = 2116cm sq.

Let's also assume the octogon is 'perfect', in other words the corners intersect at in neat thirds, in other words: 46 / 3 = 15cm.
Therefore the 4 triangles are actually 2 squares @ 15cm, hence the area of the corners = 2 x (15 x 15) = 450cm sq.

The area of the octogon is the square with the corners removed: 2116 - 450 = 1666 cm sq.

So, if the height of the tank is say 50cm, the volume would be 50 x 1666 = 83,300 cm cubed or 83 Litres (22 US Gallons).

(in fact, if the height were also a neat 46cm high, you'd have a 20 US Gallon tank).

Clear as mud, no?

Andy
 
get a measuring jug, pour water in until it's full noting how many litres you put in :hyper: :D
 
An Octogon is basically a square with the corners chopped off.
Each corner is 4 triangles, 4 triangles added together = 2 squares.
So the area is a big square with 2 little squares removed from it.

Let's assume that 46cm refers to the overall base width (& therefore length),
this would otherwise make a square whose area would be 46 x 46 = 2116cm sq.

Let's also assume the octogon is 'perfect', in other words the corners intersect at in neat thirds, in other words: 46 / 3 = 15cm.
Therefore the 4 triangles are actually 2 squares @ 15cm, hence the area of the corners = 2 x (15 x 15) = 450cm sq.

The area of the octogon is the square with the corners removed: 2116 - 450 = 1666 cm sq.

So, if the height of the tank is say 50cm, the volume would be 50 x 1666 = 83,300 cm cubed or 83 Litres (22 US Gallons).

(in fact, if the height were also a neat 46cm high, you'd have a 20 US Gallon tank).

Clear as mud, no?

Andy

clear as mud...yes!!!
 
To determine the surface area of an octagonal tank you need to know its length (L), its width (W), the length of the front pane (X) and the length of the side or end pane (Y).

Calculation form

The formula for surface area is then:

Area = 0.5(W.L + W.X + Y.L - X.Y)

ie: Multiply the width of the tank by its length and record the answer. Multiply the width of the tank by the length of the front pane and record. Multiply the length of the tank by the length of the end pane and record. Add these three numbers together, record. Mulitply the length of the front pane by the length of the end pane. Subtract this number from your previous answer, then divide by two to get the surface area.

For a round octagonal the length of the side and front panes will be equal (ie Y=X). However, this does not make the resulting maths much easier! The new equation is:

Area = 0.5(W.L + W.X + X.L - X.X)

Or simply follow the instructions as above.


got this from here check it out, tank sizes
 

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