Scott Sherratt writes:

Yes, I too have heard that the pool filter stuff
is processed differently and not the best stuff to have in your
environment. It also builds up, and I really don't want a layer of
this stuff building up on the lawn with the kids playing in it,
creating dust, breathing it etc.

Since you are being so reasonable about airborne silica, you will of course
avoid the beach, especially on breezy days.