I have a 15 ft intex pool and I brought low side up a few inches using a method I found online at levelgroundpool.com I did wet down the sand and compacted it good though.
So far so good, but if I have problems I will scrape off the high side as suggested. I still will need some sand though as our very hard clay would be nearly impossible to smooth level.
I think for a larger pool or a pool set up for more than a few months, leveling out the soil to a uniform hard bed would be absolutely necessary.