Pressure foam under large aquarium advice

[bradleyheathhays]

Setting up a 72" long 125 gal on a support I already know is irregular so I need to compensate all that I can. I've run up on this Youtube video showing the use of what is called pressure foam or possibly polystrom to help compensate for my kind of tank support issue. I've searched a couple online aquarium supply stores but I haven't been able to turn up any such product.

Here's the video...
Make sure you have polystrom under you aquarium or it may c - YouTube

Did a search on polystrom and it seems like it's out of Australia, and I'm guessing there's a US equivalent.

Does anyone know where I should look for this kind of foam?

Thanks