Considering buying a pool, need advice

[Watermom]

I'm not sure what to tell you to use to fill a low spot. But regarding what goes under the pool -- foam or sand --- how about both? That is what we always do. Put a sand bed down first with foam on top of that.

[babzog]

I could do both... but why would I want both? Assuming I get the soil level where the pool will go, what advantage will sand under the foam provide? It's easy enough for me to go get a few tractor buckets worth to do that, just curious what advantage I will gain?

What sort of foam should I use? Let's say I walk into Home Depot, what should I ask for? Thickness, type?