My biggest problem with gravel, and leven arger size material like pea gravel, is that detritus can work its way between the large interstitial spaces, and create pockets of rotting material, that after a while belch hydrogen sulfide gases, and generally deteriorate water quality.
Play sand is too fine though, and also compacts.
For me the solution is PFS.
It allows detritus to rest on its surface where can easily be vacuumed up, before it gets a chance to deteriorate water quatily,
but is heavy enough to fall back to the substrate, before it gets a chance to get sucked in to filters, and ruin filter impellers.
I got PFS from an abrasives dealer much more economically than high cost than LFSs.

