Spinosad. I tried the lady bug thing. no real results.... i released 4500 in the tent and left them closed up in there for over a month. still have issues.
Probably thrips though.. if so be careful. they will eat your leaves.
Fungus Gnats do not live in the soil. They lay eggs in it and the larvae live in it until they grow up and fly away. The larvae look like tiny white worms, not like gnats.
I used a product called mosquito dunks, the BT mentioned above is the active ingredient. I also did a soil drench with some neem at 3ml/gal. Have only seen a few gnats on my fly strip since doing this.
I just put a layer of sand or vermaculite about 1-2 inches deep and the little bastards can't get in or out and die off in a few days btw cheap soils always have mad fungus gnats...
I had gnats and i picked up some stuff called gnat nix. Serves the same purpose as sand or vermiculite but it is what me local hydro store recommend for organic growing. It's pulverized lava glass or something but it is safe to touch but don't breath the dust when top dressing your pots. Put it in 2 weeks ago and haven't seen a gnat in one week.
From what I have heard H2O2 kills not only the larva of the gnats but all the beneficial bacteria in the soil as well. Do some research before deciding on that solution.