However, I do notice that GC has
ZeoBrite noted in his sand filter (in his signature), so he's adding that to his sand or entirely replacing his sand with it.
Or perhaps he stopped doing so and hasn't updated his signature.
Zeobrite is reportedly an upgrade to sand, a mineral mixture that supposedly filters better than sand.
Having no experience with it, I cannot comment on its effect.
I hope GC can follow up on this.
As you read on TFP about adding DE to a sand filter, it is done to filter out particles down to a smaller size.
Not everyone notices the difference, and not everyone cares about the difference. But those that care often go the extra mile.
It's a completely personal choice, and not at all necessary, assuming your sand filter is working appropriately.