From the pictures it doesn't look like the center of the tank was touching the tank at all. Just discussing this with my brother in law who is a mechanical engineer. The foam is a good things it will distribute the weight over a larger area if the bottom actually touches the foam. You have either 1000 pounds pressing on 142" of frame or over 1142 square inches if the whole bottom. Having said that he said that foam is not always homogenous and could have had a high spot at any point under the tank that could have caused the failure. Or a cutting or manufacturing defect.
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