Expandable liner pad?

We live in the Northwest United States and we are getting ready to replace our liner; we have a few questions about buying and installing a liner pad or foam. We have a bowl shaped, 24’ above ground pool with an expandable bottom with a depth of 72”.
Does anyone have suggestions in regards to what type material we should use, and how to install it for an expandable bottom?
We were thinking of trying to buy a ‘geotextile’ fabric in bulk and cut it to suit our needs. Has anybody tried this idea and does anyone know of a source where the fabric can be purchased?
Thanks for your time.
cjo12

I do not know about geotextile fabric, but hopefully someone will.

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Thanks Watermom,

After more research, we discovered that gorilla pads are made out of geotextile fabric. It is used during road construction to help control drainage and soil erosion.
Our solution was to buy two different size pads, one for the expandable bottom and the other we will cut and fit the smaller pad into the center. Hope it works.

cjo12