Is it just me or so the actual water volume in the tank less than advertised? I have a 50 gallon IM AIO, and I think the total amount of water I actually fit into it was only around 35 gallons. I have a rock structure and filters in the back, but it took up a lot more room than I thought.
Is this normal??
It is 100% normal!
In fact, the industry standard for a LONG time has been to advertise a tank by the
volume it displaces, not it’s actual
capacity!
That is, they advertise the tank based on outside dimensions…. (A 6’x2’x2’ rimmed 180g tank is actually closer to 164g, filled to the brim!) usually, this maths out to 10-15% larger than the actual realistic filled system volume…
Then you consider the tank’s actual operating water height, subtract the bottom glass pane’s thickness, include displacement of all the AIO dividers, their different water heights, displacement of rock/sand/equipment…
35g is probably pretty spot on for your system!
(As you can probably imagine, this makes speccing equipment, pumps, and even livestock quite confusing! — best bet is just assuming that most brands will list the advertised tank volume, not the actual tank capacity for their products! [following the “bigger number better” sales trend…])
