keep in mind if you want your organic soil to thrive you want it living! gnats are actually a good sign until they are numerous, it means that you have fungus in your soil the larvae are feeding on! quite possibly Glomus, which is an essential beneficial fungi that wraps itself in a thick white type of webbing in your soil. if you want a Healthy soil for healthy plants you should consider feeding the fungus that inhabit the soil with beneficial Humate teas. You want mykos and azos, and its an excellent idea to get a good colony of Hypoaspis going to protect your soil from insects in general before there are any indications of an infestation. Natural sugars from molasses are important to the plant and bacterium too! Good luck on Living Organic Soil!