I won't fill up the tank sitting on the stand you have. Even a perfect tank may split a seam or the glass panels fracture.
The stand has no center support; you can already see a slight sag in the center.
The pink foam is also too stiff for a flat bottom tank. I would guess the pressure of the tank bottom on the stand is less than 1.5lbs/sq-inch. I tested the pink foam and that needs > 25lbs/inch just to make a small dent in it. The blue foam isn't much better at 15lbs/inch.

The stand has no center support; you can already see a slight sag in the center.
The pink foam is also too stiff for a flat bottom tank. I would guess the pressure of the tank bottom on the stand is less than 1.5lbs/sq-inch. I tested the pink foam and that needs > 25lbs/inch just to make a small dent in it. The blue foam isn't much better at 15lbs/inch.
