The sand works but it's a pain to deal with, as is perlite.
So, I tried reflectix covers for the soil.
Not good, didn't breathe.
So I researched FGs.
Turns out they hunt for decaying materials by scent the way mosquitoes do for CO2.
Well I've used dryer sheets to repel mosquitoes and yellowjackets.
And they breathe very well.
Started using square pots and the dryer sheets fit them perfectly.
I tear them half way through the middle an pull that around the stem
Lift them to water and change them once a month.
Even when the scent repellent wears thin they still present a barrier to would be egg layers.
Been using them for years now. No gnats, no Root aphids.
They are dirt cheap and they work.
I prefer Kirkland to Bounce.
Less perfume in Kirkland and the perfume is not what makes it work.
That's just for human noses.
It seems to be the surfactant that repels.
And the tight weave that prevents