Hey there VikRik, this stuff could easily poison you and your plants. First off, it's silica, breathe in too much of that over time and you get hospitalized . Second Diatomaceous Earth is at minimum pH > 7 that means that over time you could end up with ph problem - so just keep that in mind. Usually this kind of thing is used outside, I make a thick circle with it around some plants and it keeps things like slugs and afids away. For fungus gnats indoors it could work, but it comes with baggage. The easiest thing to do to protect against fungus gnats is simply to not over water. Fugus gnats need that long period of humidity to reproduce and hatch, so if you follow a strict wet dry cycle you'll be able to manage it. If you have access to beneficial bacterial, just add them to the watering. Doing that even if you get an outbreak it wont be so bad, you're looking for bacilus subtilis, bacilus thurengensis and bacilus thurengensis and Mycorrzhia. Hope this helps ! 🚀