Best thing hands down to have 0 gnats or root aphids is Bacillus thuringiensis or "mosquito dunks" i crush it up the mosi dunks in a ziploc bag and sprinkle 1/2 teaspoon of dunk powder per 3 gallon pot. Mix it in soil or coco and you wont see even 1 gnat GUARANTEED!! Do this in every pot. its...