Calculate the volume of a 5 sided aquarium

  • #1
I haven't had fish for many years, but finally have the time to get back into it. I've missed the joys of watching a world that fascinates me, & am soo happy. My problem lies in figuring out the size of the tank I got, so I can determine filter, plants, fish, etc. It is a 5 sided corner unit, but I haven't been able to find one the same shape to determine how to calculate, & I'm afraid my math is rusty. The tanks 2 corner sides are 22", each of the three front panels are 13", and depth is 24". These are inside measurements. I've only ever had standard rectangular tanks before & am completely lost. Any help would be greatly appreciated
  • #2
Without knowing the shapes of each side it would be very difficult to calculate, if not impossible. If you could take a picture so I could see which measurement goes where, I could help.
  • Thread Starter
  • #3
I don't have it here yet, so can't post a picture, but maybe I can explain more clearly. It is a corner hexagonal tank. The height of the tank is 24". It has 2 panels of 22" long, with a 90 degree angle between them..this fits into a corner of a room & so extends 22" from the corner on each side. The front, that would not be on the wall, has 3 panels, each being 13" long. It's like a 22" square tank, but with one corner taken off. There are no tapers, the tank is the same size at the top as at the bottom. I know I learned how to do this in school, but that was a long time ago

If this only succeeds in being more confusing, I apologize, & will take a picture as soon as I can.
  • #4
I think I understand...if you look at it from the top, does it look like a triangle (the part that goes into the corner) attached to a square or to a trapezoid? As in, when viewed from the top, are the front three panels joined at right angles, or are they angled outwards more? It doesn't really matter for the calculations, but if I can see it more clearly, it always helps I'm out now, but when I get back, I'll sketch a picture and calculate it and let you know. (I'm studying to be an engineer, so this is like a fun logic problem. ) Unless of course someone beats me to it, but at least if our answers are the same, you can be pretty sure they're right.
  • #5


If I understand correctly. My estimate would be around 37-40 gallons.
  • #6
Ohh the picture helps immensely! I calculate 38.37 gallons.
  • Thread Starter
  • #7
Thanks! That's the shape. A visual is so much better. But my brain is still trying to remember how to do this calculation. The best I could do was to figure out the volume of a square tank and subtract the volume of the missing corner. In other words..
but my answer is different than both of yours, so maybe my method doesn't work. Could you tell me how you came to this answer, just so my brain can stop trying
  • #8
I got 46ish gallons as well... so I don't know. I did the tank as a rectangle minus the corner as well...
  • #9
The volume of a triangular prism is 0.5 x altitude x base x height

Kimszoo - I think you may have calculated the volume like a cube ()
  • #10
There are several ways to calculate it, but yes it's 46
  • #11
Alright, new plan: Get a bucket with measured volume. Fill the tank, count the gallons. You'll have time while the tank is cycling to figure out the stock.
  • #12
Smartphones are only useful if you know how to use them....I have a unit converter app that I used to convert the volume in in^3 to gallons, and I had accidentally selected "imperial" gallons rather than standard. I get 44 gallons on the nose. (If you're curious about your tank's volume in imperial gallons, there you go. )
  • Thread Starter
  • #13
Thank you everyone, it was just one of those things that was going tpo drive me nuts until I figured it out I didn't use a smartphone, forget about that function lol I used my kids' plain jane calculator

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