Gap between tank and stand, need a solution

[smokinreefer]

Hey everyone,

Have a problem with a new tank and stand.

This is a big tank at 9' long.
The stand is a metal stand purchased through tank builder, for warranty.
The tank has a piece of plywood attached to the bottom.
Instructions from builder were to place tank directly onto the stand.
I paid professional movers to bring this in and put it in place.

The tank rests on the stand on both ends and on the 2 cross braces of the stand.

However, the tank barely touches the stand on the 2 x 9' lengths.
Builder says 1 credit card thickness of gap is acceptable.
One side is particularly bad and I can fit 2 credit cards in the gap (for probably over 2 feet) in the center of the 9' span.

Any out of the box ideas on how to fix this?
I don't feel comfortable doing a water test on this beast until I can resolve this issue.

Only thing I thought of was to fill the gap with spray foam...