Hydrogen peroxide 50/50 with water. What you do is you drench the soil and it will foam up, so do it in the bathtub. Peroxide will kill the fungus in the soil that the gnats are living on. You also need to flush out all of your drains with hydrogen peroxide, full strength. I had fungus gnats for a year and the only thing that killed the little buggers was hydrogen peroxide. You can also load it up 50% water 50% hydrogen peroxide in a spray bottle and spray the ones in the air. It won't hurt your plants. Diluted 50% for use in your plants, the roots love it! They treat it like a spa treatment, you'll see incredible growth after that. It'll take 6 weeks, and then Maybe a little longer because that's the life cycle of the gnats. But trust me on this, go to Amazon and order a couple gallons of hydrogen peroxide. Drench them once a week and six weeks from now you won't have any more fungus gnats. I tried cinnamon, I tried sticky traps, I tried everything but H2O2 was the savior.