Mosquito dunks, soak that shit for a couple days prior to watering. I had them really really bad, I'm down to just a few now and I haven't even used my mosquito dunk water yet. This is what I do, maybe it will work for you. I take a clear glass, pour a fresh sprite into it, add some dish soap, and I add about a handful of raw sugar, mix it up and it will foam. Then I set that in between my plants, I drop sand on the top soil so no more new gnats can lay eggs, then I stop watering for about a week, letting the gnats either die or drown. Just my 2 cents. You can also use neem oil if your plants are still in veg