These gnat's have been giving me the blues for several crops now. I haven't been able to totally rid my garden of them yet, however, I have kept them to very few by cleaning the saucers under the plants with hot soap and water (every time I water) and then covering the bottom of the saucer with AzaMax. I also found that the more holes in the pot, the worse they are because they crawl in and out of the dirt through the holes. The fabric pots are the best because they can't go in thru the bottom, but they take a little getting used to. Also make sure to spray and wipe the bottom of your grow room because they love to breed under the saucers. Basically if you can keep it CLEAN, they won't get the upper hand.