Yes, it could be less but...
Because I'd never built one before. And I wanted it rimless,
with 4 sides embrace the base (ADA & German style), not sitting on it.
The glass sheets I got were a bit off in size (1-1.5 mm).
So I couldn't just make some beads of silicone then putting together the glass sheets.
I had to pre-positioned all the sheets, pre-adjusted them to compensate for the imperfections
and secured them in place. Then I injected silicone into the spaces in between the sheets.
Quite wasteful since most of it was on the masking tapes and removed.
But I was satisfied with the result as the first aquarium I'd ever built.