One of the reasons to use PFS, as opposed to lighter weight types like "play sand", is the lighter weight sands can more easily be swept into filters, where they pitt and ruin impellers. 4 decades ago when I first started to use sand, I tried play sand, and ditched it after the impellers in my pumps became useless. PFS is more dense so it quickly sinks after being backwashed, so if you keep larger fish like cichlids that can sweep sand up with their movements, or mouth it and spit it out in clouds, PFS is less likely to get sucked into filter siphons or tubes. If you have smaller community fish, this may not be a concern.