My understanding is that many add Steinernema feltiae nematodes. Good for fungus gnats. I was going to use nematodes also, but the nematodes don't deal with very nasty root aphids, and they're by bigger concern. For aphids, Beauveria bassiana fungus is really supposed to be great, but it's damned expensive.
So I'm mixing the SuperSoil with Organic Pyrethrum and adding one more dose when I stir the SS after a week. I'm going to treat the Roots soil on top as well. Then I'm top dressing the pails with food grade Diatomaceous Earth. If I find the fungus cheaper (Botanigard or Naturalis-O), I'll add that also. Hit these pests from many angles.