can foam be used for padding?

Hey all,
I just got an 30 foot pool. I am nearing the end of the ground work. In my pool setup book I read you can use 3/4 inch foam sheets for padding in the bottom. Has anyone done this? It would save me a LOT of work if I could. I have been told by some people it will kill my liner also I have been told it's better ( because it can't wash out ). As for padding I don't really have to have a super soft feel. Has anyone done this before? I am using the foam pool cove.
Thanks Mlt2