When I say one thousand, its an approximate measurement. But that's a good calculator
As said, there's no real measurement as these tanks are custom made and you usually demand the size. If its a reef, I would go longer and shorter in height. A predator tank would be a bit higher and larger. A community tank(huuuuuuuuuuuuu...uuuuuu...gggeee) would be "skinnier", longer and shorter.
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