On 27 Mar, 03:01, "Dan White" wrote:
I was thinking of making a tank stand for a 75 gallon fish tank,
which will weigh well over 700 lbs.

Be careful of designs from a site about reptiles! Aquaria look a lot
like vivaria and terraria but they're full of water and the weight
issues are much more significant.

I'm puzzled by what's supporting the bottom glass in this design? The
usual failure mode of aquaria isn't over-loading the glass, it's
excessive point loads on the underside, where all the force from a
narrow frame is in one small area.

When you fill a big tank (I mean a _big_ tank), watch it in polarized
light and look for the stress patterns as you fill gradually. If it
looks to have a local problem, fix it before continuing.