Our AG pool was installed just over 2 yrs ago. The installer leveled the ground and had us get some masonry sand for the bottom. We noticed this year that under the pool looks like the Canyonlands!! All the dirt settles into the canyons and it is difficult to vacuum them. Is this a common thing to happen or did the installer not do things correctly? I can't tell if the canyons are caused from ground cracks under the pool or if the sand ran like rivers during times of heavy rain. I haven't noticed ground cracks other places around the property though we are officially in a drought. But, I can't figure out how the rain water would get under to pool to make the sand run. I am sure that we don't have leaks since we never lost any water this year.

Any thoughts??